Goo gone or goof off. Test in an inconspicuous area in case it reacts badly with the paint.

Looks like a water slide decal.

The "flea market"? Where?
I wish I could find a nice wedgehead at the local flea market!

I find WD40 really good for sticker removal-it may take a few applications and some appropriate rubbing. If you are doing it on the machine make sure you have protective cloths to prevent any runs on the pdf.

I second this. It does a good job at removing the adhesive without removing the paint. I've removed several operator decals on ball aprons with it.

If the WD 40 doesn’t work, I’d moisten the edges with mineral spirits and gently work with a new single edge razor blade. Good Gone is ok but Goof Off is basically benzene and xylene and will eat into the paint.

As a painting contractor I’m constantly having to remove stickers and tape. It all depends on the surface and how strong the adhesive is. Either way, you might lose some of the webbing.

It looks like a water slide decal. What would a person use to remove that? Water?

Take that apron off of the game. When using any chemicals or water near the playfield, and the inside of the cabinet.

I would try to soak the apron in warm water. To soften up the decal. the enamel paint should hold up to the water. The real problem is the webbing, it does come off fairly easily. Looking at the scrape marks, it appears some paint loss has happened already.