Two quesions actually: (1991 300E)

First: I took my car in to get the CEL read, and they said it was a faulty oxygen sensor. I replaced the oxygen sensor today, and everything went well. My question is this: is there anyway to clear the Check Engine Light so I can assure myself that i fixed the problem (if the light stays off)? I'd rather not have to take it in to get cleared as I'm sure they would figure out someway to charge me something.

Second: Is there anything i need to adjust, or change after installing a new oxygen sensor?

Thanks in advance.
-E

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I love my cars to death but my wallet sure doesn't.