While not tried, I would expect that if the RAP is up and connected to the controller, you should be able to reprovision the AP and then disable the Remote AP option. You probably will need to change the master discovery as well to the internal hostname/IP during that step.
Doesn't need an additional explanation that you have a single chance to move the AP to non-remote and get the master discovery correct. I would try with an accessible AP before you do this with many or inaccessible APs.