Keeter59.....A friend just purchased a used coach and was amazed at the sealant on the roof. Apparently, the previous owner paid an RV shop to reseal the coach each year. All they did was keep reapplying Dicor (white self leveling stuff) on the roof. It was a mess.
The Dicor can be easily removed. Just heat the Dicor with a heat gun and use a plastic putty knife to scrape it off. It will come off pretty quick with a small amount of heat. Once the bulk of it is removed, you can use "Goof Off" or Goo Gone" to wipe off the residue. You can reseal, more carefully, with Dicor.
Your other issue is the clear coat has gone bad. This has been an issue with many brands for several years. If you go to RV shows, you'll see many brands now advertising 4-6 coats of clear to combat this issue and as a selling point.
Last month, I got tired of repairing mine and took it to an RV paint shop. They sanded and repainted the all four sides of the roof line. Depending on where you live, this can cost between $1000.00 to $4000.00. If you're handy, you can repaint yourself, but the issue will return if you don't spray it well and put on lots of clear.
Don & Mary
2019 Newmar Dutch Star 4018 - All Electric
2019 Ford Raptor Crew Cab