There is no mention made about Tinker in the Getting Started section precisely because for the cube, you're not going to be using tinker at all. So there's really no need to do this now, since you went ahead and followed instructions posted elsewhere that encouraged using Tinker for other purposes.
Also, according to their instructions, the phone app detects and warns the user about the target device not running the Tinker firmware, and asks for confirmation on overwriting the Tinker firmware to that device:
Anyway, reflashing the original demos it's always as easy as switching your photon to Safe Mode, then reflashing the demo code over the air from the gallery.
Tinker is a product of Particle Industries, so I suggest you post further questions regarding this functionality in their forums.