A real easy way to clean the outside of the awning, After you have soaked of course. IF you have a manual awning. Unroll it, Unhook it from the side of the RV, let the arm slide under the RV and let it hang straight down. Now you can use the side of the RV to hold the awning steady, and scrub your little heart out. I do mine that way. The underside is tougher.
Of course IF you have a walk on roof. Roll out the awning unhook the arms from the RV, and bring it back over the top, and lay it out. Scrub your little heart out.