Forgive me for taking this seriously in any way, but what would be the point in removing the ink from $100 bills? To make $500 bills? Good luck transacting those.
If you plan to print counterfeit $500 bills, you may as well print the $1,000, $5,000, or $10,000 bill (good old Salmon P. Chase). They were all discontinued in 1969.
Then once it's out of the country, the bills can be soaked in a magic fluid that will remove the black ink, but keep the original ink in place.
They say that conmen are the easiest to con. I guess this is an excellent example.