tomtomtom123 is correct. First, the rim mfr did some weight optimization vs strength. Removing metal arbitrarily is going to give you weak rims. On an ebike? Nein danke.

Second, there is no way to do the grinding with sufficient precision, without removing the rim and mounting it on a lathe face plate. Precision metal cutting requires tools and jigs and fixtures that are exceptionally rigid and a spoked bike wheel doesn't qualify.

So, I suspect that you'd end up with an aesthetically unsatisfactory wheel with really uneven grinding marks that would break prematurely.

read tomtomtom123's post: make sure that the wheel beads are in the center well of the rim when you mount the things. I had huge problems with my tires and rims until I remembered this.