I need to go from 220v to 110v on spa heater. 3 line set up, and I have instructions on 110V with White jumper on Neut and l2, black on L1... 220v also had Red on L2... what do I do with that unused wire?

Without seeing the instructions it is impossible to tell.

Can you scan the instructions and post them, or maybe find them online and provide a link?

Echoing Stan, without more details we are dead in the water.

However, you should not take a 120Vac tap off a line (be l1 or l2) unless you have documented proof from the manufacturer of the spa authorizing such a change.

That is considered to be product tampering.