My car was painted with a single stage enamel over the original 1970 enamel paint with out primer. I have sanded the car twice with 220 . There are places I cut through to the original paint and some places not. After washing the car down and using a grease and wax remover, I am still getting paint on my towels. The
Do I need to completely remover the second coat of paint?

Don't worry about the colour on your towels, it's just the exposed paint.

Seal the whole lot with epoxy and then do your high build primer.

I bought a different wax and grease remover and seemed to do a better job.

Its called prep-all by kleen strip . It evaporates rather quickly when wiping it and removed 99% of the paint dust.

The stuff sold in auto part stores is worthless.