1992 Grand Am Overheating

I have a 1992 I recently had to replace the water pump , because it went out. ever since i replaced it It still has been over heating so i removed the thermostat and the over heating stopped for a few days now it has started over heating again. Can anyone please give any ide at what is going on?

Did you get all the air out of the system when you refilled the radiator after replacing the water pump?

How do I get the air out of the sytem?