Regarding continue persuing btech due to covid 19 pandemic with govt job

you can approach  your higher authorities for denial reason of leave 

The degree is always valid when you have completed a course. and was successful in the qualifying examination.

Taking a course when authorities refused permission is a violation of disciplinary rules and regulations.

Both issues are different.  But, when you submit your qualification certificate for registering in your personal file, someone may then point out, and then either they may ignore or seek a formal explanation and you may draft a convincing explanation.  But the employer can not terminate you or invalidate your degree as employers can not show such reasons for neglecting your duty due to the course's pursuit after you have completed the course.

The degree you are pursuing is surely valid on your successful completion of the same. If it comes to it, you can complete it by applying eligible leave or on loss of pay. Now point is whether the Department accepts the degree and makes a note under your academic qualifications in your service book in the background of earlier denial of study leave.

More often than not bureaucrats world over, especially in India,  do not think like humans but only see papers and write orders routinely without appreciating the fact that each request is a unique one and as such to be acted upon consciously but not in a clerical manner. Now and then they need a tap on the head .

The refusal of study leave might have been because by then  you just joined the job and didn't have eligible leave. As of now you may be eligible for leave. If you don't have leave, they can give permission for a reasonable period atleast for attending exams on loss of pay.   The organisation must be having a trade union. You may approach the Union officials and seek their intervention and help to sort out the matter.

Yes, the validity of the educational qualification  is unrelated to the whims and fancies of the official superior.

Moreover, getting educated and continuing education is the ordinary right of a citizen; it forms integral part of the Fundamental Right of Right  to Leave. Such a right of a public servant could only be restricted or otherwise interfered only on the strength of statutory provision duly notified under the provisions of Article 309 of the Constitution. No authority is empowered to initiate disciplinary proceedings just because the Government servant continued with studies without, in any way, adversely affecting the discharge of his duties or compromising his devotion to duty.

If need be, you may seek information under the RTI as to the provision of the Conduct Rules or any statutory provisions which mandates that a public servant need to obtain permission for joining any course of study or for continuing a course of study. There, certainly, cannot be satisfactory reply.

It is incorrect you had applied study leave. Apply for any other leave, as applicable. 

In the case of educational institutions, if the student states that he is employed, the admission will be granted only after receiving NOC from the employer.  Each and every employer has its own disciplinary rules and regulations (Generally copy/paste application from other institution) and getting prior permission is mandatory in case of reputed institutions including Govt.  The NOC is also subject to execution of an agreement that such permission may not construe any other rights against transfers, and subject to assurance that his regular assigned duties are not hampered due to the permission.

Shri Abhishek was already prosecuting B.Tech and got the job based on a lower qualification ie. Diploma. Therefore, obtaining prior permission or NOC for studying for higher qualification does not arise. It is on record, he sought permission and it was rejected. Now he is worried about what will be the validity of the Degree once he obtains it as he is in Government Service whose authorities did not give permission.

I reiterate my view that his degree has every validity permission or NOC from his Employer notwithstanding who came into the picture in the middle of the Course. Now his worry is allayed that the degree is very much valid and he can seek other jobs and take up with the present Employer to record his accomplishment if necessary escalating the matter to further higher authorities. No Employer in his right mind shall deny his Employees in getting higher qualifications just for the mere formality of NOC not obtained which in this particular case is not applicable as the queriest got the job while prosecuting such higher studies and the queries did his duty of informing of his position and sought NOC which was unfortunately declined. Just because he got the job and the present employer did not give NOC or permission he cannot stop the course. The queriest did a commendable job and continued to prosecute through home study and online classes etc. The employer should be appreciating his efforts instead of coming in his way. If the matter is properly taken up and escalated to further higher authorities beyond the present bureaucratic immediate bosses obsessed with rules and unable to see beyond I am sure Abhishek shall get a decision in his favor.

Yes, I do agree with Shri G L N Prasad that NOC does not confer any right to the Employee in the matter of posting etc.

But sir my question is that ....I done my one semester i.e 7th ....online due to covid . And give exam on leave of my account. Is this is misconduct or not . Because online study have done in many ways. But matter is here attendance in collage have given . Is there any disciplinary action in future. I have left my degree or not

The definite answer is that continuing education or joining a course of study, by itself, is  not misconduct.

Sir , I have done online classes with govt job due to school shutdown.But teacher make record on attendance.so but suggestion on it what I do 

You can not expect from members about the probable, future action of your employer.  In normal circumstances, the employer never cares about the employee's general outside conduct and is concerned with only his internal performance of his assigned duties.  But, there are killjoy bosses, that wanted to teach a lesson to employees and to take them into his grips, and showing their authority.  First, shed down fears and continue to perform your duties, and come back to the same post and report if there is retaliatory action by the employer.  Please do not assume things and expect guidance.