While you can exchange the internal hinge assembly for the VESA mount version its a god awful job as you need to take the whole system apart to get to it!

The better and cheaper approach is to find one of the 3rd party clamp on VESA mounts these connect to the hole in the foot VIVO Adapter VESA Mount Kit

If you are really set on wanting to remove the foot in its entirety, I know of a few folks who bought another foot cutting it down and TIG welding a machined VESA mount to it. I’ve also seen a removable foot design made so the foot could be taken off for shipping!