Theoretically, yeah, I guess that's what you'd do if it was possible.
But removing a fretboard and sliding it up higher on the neck probably isn't practical and may not even be possible.
For one thing, the fretboard is presumably tapered, as is the neck, so even if you were to manage to get the fretboard off the neck in one piece, the taper is thinner the nearer the nut you get. So sliding it toward the headstock would leave you with a fretboard too thin from side to side, to cover the neck. And the headstock isn't going to be level with the rest of the neck. You'd also have a gap at the body end of the fretboard you'd have to do something with. And the truss rod nut access would have to be attended to. And the neck pocket (if it's a bolt-on) would have to be filled. And you may not have enough body/neck contact to get a good neck joint. You see where I'm going with this...
[Edit: I assumed you meant on an existing guitar. If you're designing a new one, then you have some options. ]