My Sign shop uses Rapid Remover for removing the adhesive residue. It is a citrus based remover.
You still have to do the handy work of getting the vinyl off, the rapid remover does not help with that. We use a blow dryer to soften the glue and an exacto knife to lift up an edge and pull it up by hand, Newbies may want to get a plastic scraper knife.
After a large job of pulling up vinyl your fingers will get raw feeling just from the friction of pulling. Facing the job to the sun is also very helpful if at all possible the warmer that vinyl the easier to remove. After the vinyl is off spray some Rapid remover on the glue residue and leave it on for at least 60 seconds. Spray on more where ever it starts to look dry. You want it to look like the consistency of boogers..not appealing but when its there then is the time to scrape it off in to a paper towel. Repeat as necessary and for the final bits of residue wipe it down with a paper towel sprayed with the stuff. Buff it dry and let the residual evaporate, if you wash it with water to soon it goes all milky looking, doesn't hurt anything just looks scary. it all washes off, evaporation is just easier
Also worth noting it does evaporate quite quickly, working in the shade is better for this part...or just keep spraying more on
It does not hurt clear coats we use it on vehicles all the time, and purely by accident I just discovered it is amazing at removing old vulkem sealer from around the windows and panels on my '69 safari I am currently using it everywhere. I will post a thread on it later. Here's my nice, shiny, not covered it 40 years of adhesive light fixture after I was done
I've also done one round of it on the sticky vinyl walls to remove the grimy feeling it has helped but the stickyness is still there, I will give it another couple goes to see if I can improve it more. It does not hurt the top of the vinyl
We get ours from Express sign products in Canada, Want to try some out before buying a bunch, call around to your neighbourhood sign shops and ask if they'll let you put a bit in a bottle to try out.