You need to find the file manager on your phone, then click android, data and there among all the application files you are looking for your game.
I finally found some answer withing the rpg maker forum.
But they are BAD ones....
Apparently the port apk stores save files into an inaccessible folder, so nothing can do.
During the developing process I sometimes make changes that need a fresh start (like I did in version 0.11, where I added a new plugin incompatible witho ld saves);
With the windows version I can easily fix this by adding a save file, but it seems like there is no workaround for the android version, I'm terribly sorry -.-'