How to make some defence witnesses hostile

As per your statement of facts, these are the defence witnesses who have been called on the request of the accused himself and now the accused does not want to examine them as defence witness. The solution is to drop them as defence witnesses by making an application; or when they appear in court, the counsel for the accused can make the statement that he does not want to examine them. The court will generally not force the accused to examine certain persons as defence witnesses. It is the prerogative of the accused who he wants to examine as his defence witnesses.