Some Auto companys like GM, Ford and Nissan have a dye solution to put on waxed bumpers. I have used Meguiar's #39 Heavy Duty Vinyl Cleaner in the past to get wax off of plastic.

 

If i remember . It's peanut butter & jelly?

 

Might try rubbing alcohol. Naked chicks are for waxing cars. Here's mine:

 

Depends on the plastic too...

I've gotten wax off of black plastic with detailer's spray (any brand) and "Flash Black".
Then again, many years ago I had a Chevy S-10 and got wax on the plastic bumper trim. Nothing on the face of the planet would ever get it off.

 

H2O

 

Mothers back to black works on jeep flares when they discolor might be worth a shot!

 

I've been using Mr. Clean Magic eraser for years on my truck trim, absolutely the best thing I have found.

 

wd-40 and peanut butter work&nbsp\\;&nbsp\\;&nbsp\\;&nbsp\\;

 

If it's black plastic try mother's "back in black" from any auto parts dealer or Wal-mart.&nbsp\\; Not only gets rid of the wax buildup, it keeps the black so dark it looks almost wet.

 

peanut butter, who would have thought