@Diane *********
okay now we're getting somewhere. IF you do 90 day reporting (which has nothing to do with how long you can stay IN thailand) it means you are on an extension
AND
to leave the country correctly you need to go cancel your work permit at the dept of labor, then take that receipt and the termination paperwork to the immigration office and cancel your extension of stay.
You can do this a week before the termination date on your paperwork.