Problems With Tape

Acetone should dissolve the actual tape residue and leave the metal's toning in place. However, that thick layer of residue has probably protected the metal directly underneath it from toning at the same rate. Remove all the residue and you'll still likely have a strange square-shaped hole in the toning.

I'd still remove it anyway; I'd prefer a tape-shaped hole in the toning to a big chunk of actual tape residue sitting on my coin.

As noted by SAP. It should really work but pending on how long it has been there, more likely than not there will be that spot left looking differently.