File/buff top layer of polish to break the top coat seal.
Soak a cotton pad in acetone and place on nail.
Wrap nail in tin foil.
Soak for at least 10-15 minutes.
Remove foil & pad.
Push back the gunk that is on your nail with a nail stick.
Repeat until all polish has gone, then gently buff any remaining bits.
File and shape nails.