When PVC-E is applied to bare wood -- around a metal valve plate or
anywhere else -- it can be almost impossible to remove from the wood.

However, if the wood was sealed with shellac first, and the glue
is only around the perimeter of the plates, it's usually possible to
scrape the glue off with your fingernail.  It might take a little time,
but my experience has been that it does peel off, with no residue
remaining on the shellacked wood or the metal.

If the plates were actually glued down with PVC between the wood and
metal, not just around the perimeter, that's another story.

Art Reblitz