How to fix oil pressure error?

On older vehicles like this problems are often in the wiring rather than the component itself. Carefully take connections apart, clean them and make sure they are tight when you put them back together. Make sure grounds generally throughout the vehicle are tight and clean. Scan it for trouble codes to make sure there isn't some other problem that's causing it to send bad signals. And, if that filter is at fault, change it, don't eliminate it. Not having it in place may send a new trouble signal to the computer or confuse it into making other changes to the fuel system that will adversely affect your truck.