Mounting a small wedge is the most expedient solution.
Doing it in Carbide Create (not Pro) is rather tedious to set up — see:
Another option would be if you had a suitable V tool which was oblique enough to cut at the desired angle — I’ve done that for joinery, but it’s similarly tedious.
Doing it in Carbide Create Pro requires creating a much larger model than the inclined area and then setting the area around it to be equal, or drawing it up in greyscale and then importing a pixel image as a depth map.