You could try. But there's 2 problems with that. Firstly surviving on your own is extremely difficult. Subsistence farming is hell and without a community often ends in death after a single drought or bad crop.

And secondly the medieval era didn't have that much empty, unclaimed land that could support either farming or hunting. There were farming communities everywhere there was open space. And old forests in Europe are pretty much entirely man controlled by this point. Poaching was a serious crime because of population control and logging was also controlled.

What I'm saying is, no man is an island and very few could survive as one. There's a reason we developed society.