Employee Resigned Without Notice: Can We Legally Hold Back His Clearances?

I am working in a small-scale industry as an HR manager, and I just want to ask: In my company, an employee has resigned without any notice period, whereas in his joining letter, it is mentioned that before relieving, he has to give a 3-month notice period. Can we stop all his clearances? Or are there other methods to handle this? Please suggest.

Dear Friend,

Please review the clause in your appointment letter. Many companies practice the recovery of notice period days and will withhold clearance accordingly.