To get off of Cima SAT, you must continue to the other side of the summit and descend a short but quite steep bit of protected ferrata (i.e. so don't take off your ferrata gear at the summit). Once you've downclimbed this short section, the ferrata is now fully over and you can remove your gear.
There are several options available for your return. If you wish to return directly to Riva, then follow the signs to path 404, and this will lead you back down towards Riva, eventually reaching the Chiesetta Santa Barbara and completing the 'lollypop' section your journey. You then continue following path 404 back down to Riva. A second option is to continue up-slope at the 404 junction in the forest. This leads up to path 417 at the crest of the Rochette mountains. You can then follow path 417 all the way down to Biacesa, a small mountain town at a significantly higher elevation than Riva. If you have two cars and you like point-to-point hikes (and/or if you want to avoid having to descend the full 1200m of elevation), then this option might be for you. You'll notice that in this writeup, we chose the latter route.
Quick Reference Ferrate Route Index
rating from the newer Cicerone Guide by Fletcher and Smith
(**) Difficulty rating from older Cicerone Guide by Hofler/Werner