Tell them that you are leaving.
If you exiting Qatar within 30 days from your date of Entry you don't need an Exit permit.
You don't need a NOC letter either, in case you want keep looking for another job.
Make your calculation:
15 days Salary minus Air ticket minus QAR200 (for your business visa). If the result is still worth to fight for, try to get your salary, if not, just leave.