Seeking visa cancelation to join another job

I worked for a company in a Freezone in Dubai. I was relieved from employment by the end of April 2020 and my company paid my separation benefits by end of July 2020.

Since then, I am requesting them to cancel my visa, but my company has not taken any action. Moreover, I am the Manager on the company's trade license.

I understand from the Freezone that my company has to appoint a replacement Manager to take over from me and only then my visa can be canceled.

My Head Office does not want to continue operations here and, hence, they are not in a mood to appoint a replacement for me. Meantime, I have secured a job and need to cancel my visa.

Can you please guide me?