how to delete the dtc's from the ecm in a 1991 chevy euro lumina?

unhook battery for about a minute or two rehook and should be cleared out of computer,if comes on again need to have a scan done,or replace parts and retry the battery.

You can also buy a GM code scanner for OBD-I for about $35 at Wal-Mart or any auto parts store which will allow you to retrieve and clear the codes.