I want to cancel my appointment for corona in...

I would like to clarify to you that 
usually in companies the sponsor or the deputy only can performs  the procedures of cancelling the visa or residence. The guaranteed cannot apply without the sponsor’s permit. However, if the sponsor rejects completing the application, then you can file a complaint at the ministry of labor to prove the expiration of the employment contract.  

The sponsor or his representative (for example, in case of companies) shall do the procedures for cancelling the residence visa. The sponsor can not proceed without permission and the sponsor signature.
If the company decides to cancel the work visa for the employee, it must first refer to the Ministry of Human Resources and Emiratisation and apply for cancellation of the work contract and the worker's ID card. This application must be signed by the employer and the employee, attached by a letter signed by the worker stating that he /she has received all of his / her salary, entitlements and end of service benefits from the company.
After completing the cancellation at the Ministry of Human Resources and Emiratisation, the sponsor can only apply for cancellation of the residence visa at the general directorate of residence and foreign affairs in the competent Emirate.