^^^
I second this opinion. Don’t mess with fent tainted coke to try to do a purity wash. The risks FAR outweigh the benefits. I’m aware (and have performed) warm water washes on finely powdered crack to flush out amphetamines, caffeine and ephedrine. However, I must admit I have never heard of this working to remove fent so further research should be done before you choose to go this route.
And in direct response to your question, NO - cooking the fent tainted coke into crack will not get rid of the fent by itself. Keep in mind the number of ODs that have been reported from crack tainted with fent. Just cooking it will not wash it out.