I am in B.Sc. Forestry 2nd year. I want to change my college in same university, but my old college is not providing NOC. What can I do?

You must write to the college principal/dean asking for reasons for refusal to grant TC. If for any reason the principal does not reply to your letter you can issue legal notice through a lawyer to the school authorities. You can also proceed to high court and file writ against them.