Hello All. Anyone have advice on the following. Is there anyway to remove
grout/admix on the surface of my bathroom tile.

A previous contractor, mixed something, (Admix?) to the grout to make it
water-proof I guess, but never bother to remove the excess.

Now it's on solid, and no amount of scrubbing can take it off. Any ideas?

(I want to keep the tile, only just remove the grout left on the surface of
the bathroom floor tile.)

Thanks!