I frequently WASH deer and elk skins in the washing machine. Cold water, and laundry SOAP, not detergent. White King is one brand, Ivory Snow flakes is another.
It may take 2-3 cycles to remove all of that, but at this point it is a cheaper option than buying more leather.
I usually hang them till mostly dry, then tumble in the dryer with no heat. A couple of baseballs helps "beat" them soft as they finish drying.
For the record, deer and elk can be dyed with Rit dye. Blend different colors, experiment on scrap until you find the color you want.