is it possible to remove the stand on a2115 27 inch 2020 imac.

do i need to take the screen off in order to take this leg off?

That model woudl require a compete gutting to access the mounting point—not advised unless a pro does it. There are adapters that clamp to the existing stand without removing the stand. That is the better approach.

Those models lack the VESA mounting ability of earlier models.

Apparently it's not impossible to achieve something similar though. Read How do I put my 2017 27" iMac back on its stand - Apple Community for a cool-looking implementation.