Procedure of Cancelling my employment contract before my visa expires

Hi
I have a query,

I came to Oman for the first time on October 2019 through work visa. I have been working in a company from past 11 months. The company management had taken my original education certificates for the purpose of some approvals from ministry. Now, I'm not getting my salary from 4 months and due to family emergency, i decided to resign my job. I have given my resignation letter to my management through e-mail and i promise them i will work until my notice period.
Then our management person said that they are not accepting my resignation and i have to work until my visa expires. They said, i can go for annual leave for 1 month.
But, my family situation is too critical and i need to go and to be with my family.

Is there any rule of compulsory to work for 2 years in oman ?
Shall i approach through legally?

Please suggest me what to do.