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I've always had luck just pulling the negative cable for a couple seconds, it would reset the codes.
As far as leaving the lights on for an hour with the battery unhooked, I don't see how that would do anything. Any remaining electricity in the system would be gone as soon as you turned the lights on.
There was that one '96 Cavvy I worked on, I had to take it to AutoZone to get the code cleared, none of the traditional unhooking the battery methods were working.