Hi, Dianna. I don't understand how this "wall" thing works so I hope you see this.
If you're painting wet in wet it's easy. While it's still wet, and if the paint is thick, just scrape it off with a pallet knife, wipe with a paper towel to remove any that's left, and paint over. If it's just thin paint a paper towel or rag is all you need but if it's already drying just paint over with the correct value/colour. With wet in wet we generally use opaque colour so you don't see what's under it. You won't get the precision you can achieve with layers and glazing but you do get a more lively, paintetly look with bravura brushwork.
You seem to be already very technically skilked using layers so I'm guessing the more slap dash painterly look is what you're aftet.