HELP - Mold & Mildew for Newbie

[TryingOBrien]

First timer here - bought a pop-up (2014 Rockwood Premier 2516G) and the canvas has some black mildew/mold spots on it that I'd like to clean. The problem I see is that the Mold/Mildew looks to be on the other side of the canvas (on the canvas but on the other side - facing the vinyl).

How would I go about taking care of that? Must Unscrew, unzip and remove the sections or will a technique work to penetrate the whole canvas?

Any help is appreciated. I'm literally days old into this new venture.

Thank you in advanced!