Letter to complete exit formalities then only relieving can be issued

I am working with educational group one of my staff has resigned 1 year back and asking for relieving letter but as per the terms and condition of employment she has not served notice period even not completed exit formalities like no due. I need to send a letter to complete her exit formalities then only relieving can be issued.

You have no legal stand to ask for the notice period / not having completed the exit formalities, after lapse one year of resignation. The staff has the right to demand for service certificate.