The OFA instructions for the 9960 aren't very good. I hope you've found good instructions for deleting learned signals and KeyMoves.

When you get a second hand OFA remote, it would be best to start with a 981 reset (which is an undocumented, by OFA, full reset) to get rid of anything preprogrammed that might confuse you.

But, if you've already programmed in a lot of support for your own devices, that reset would mean you need to start all over, so some less drastic way of clearing those possible learned signals may be better.