How to clear codes?

[Steve & Kathy Enfinger]

Remember the problem I had with "check engine light" staying on ... I
found several corroded ground connections but the culprit turned out to
be the connectors to the DDEC II unit. Not visibly corroded but first
time I removed & then reconnected it fixed problem. I cleaned them well
& applied a dab of "corrosion block".

Now I need to clear all those bogus diagnostic codes. Can it be done
without hooking into test instrument?

Thanks,

Steve & Kathy Enfinger
91 WBSA
Newton, GA