Cancelling Fault Codes/Erasing Check Engine Light 1988 300TE

I had trouble starting my car tonite. I pushed the button on the OBD and the mechanic said it sounds like my fuel pump relay. I want to clear the fault
codes and turn off my check engine light. Can anone give me the sequence I need to use to do this. I did it once before but forgot how to. I know that it involves pusing the putton down for ten seconds at some point. Can anone help? Thanks.

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