As you begin to follow your would-be master, it occurs to you that ne not only neglected to make doing so a formal command, he also never forbade you from simply removing the collar entirely. As you're still barefoot on soft grass, you quite easily give him the slip before he notices, retreating to the cover of a nearby forest to hide and plan your next move.
As you catch your breath, leaning up against a tree, you ponder your situation. Despite what that text prompt said, it apparently is possible to make serious alterations to your body. If you can figure out how, not only can you undo everything that creep did, you might be able to become a man again.
The next time you see a warning about trusting someone, you are damn sure you aren't going to ignore it.
While for all intents and purposes, this is reality for you now, this particular slice seems to be an RPG, and whatever he did to you to make you compatible with the game mechanics almost certainly makes it a mathematical impossibility for you to hold your own in any sort of direct confrontation.