First thing that you should do is:
---Firm up your next venture/employment suitable to you.
--- Record the demand/threat to resign (audio/visual/witnessed/minuted) and generate irrefutable evidence, for use at appropriate time in appropriate forum. Later the onus to prove may fall on you.
Download all rules/policies that are applicable in establishment and applicable to you and narrated in appointment letter e.g; HR policy, service rules and regulations, and also record of performance, tasks assigned and performed, appreciations, incentives, awards, rewards, appraisals, attendance, salary slips etc etc
and also your duties on record ………………………showing that you had no power to sanction ;leave/increment/appoint/terminate/decide etc etc
Approach employee's/trade union leaders and a very able counsel specializing in Labor/service matters……….and generate support group.
Check if the establishment has a ‘Works Committee’.
Check if your state has asked to form ‘Grievance Redressal Committee’………….e.g; as in Karnataka.
Don’t oblige by handing over your resignation on platter.
If at all you have to resign; submit notice of resignation, mentioning effective date of resignation/LWD ( that can be even more than employer has asked or even notice) under proper acknowledgment and mention that on dated………………you have been asked to resign by Mr/Ms………………….and to give up your employment and your source of livelihood and not to come tom office from dated………….and request that this verbal demand may be called back………………………and you should be allowed to perform your duties…………….
Don’t submit undated notice of resignation/resignation as it can be used to square off your dues with notice pay.
You can send it from personal email id, followed by letter thru Redg . post.