@Iliyan **********
Everything you said is not true.
If you are on a 90 day non-B VISA, that you purchased from a Thai embassy or converted inside the country at immigration, a visa cannot be cancelled. Regardless of what happens with your job, you can stay until the end of your entry stamp.
If you are on an extension of stay that you applied for at the immigration office and the stamp in your passport says "extension of stay" then your extension ends the same time your job ends. There is no 7 days to leave.