raze, rase. Rase is the older spelling, but raze now prevails. There is some tendency to use rase still for senses, such as erase or scrape off, that are now archaic; but the distinction corresponds to no difference of etymology, & raze should be the only form.
You're doing it wrong - this is how to do it:
1555 R. Eden tr. G. F. de Oviedo y Valdés Summarie Gen. Hist. West Indies in tr. Peter Martyr of Angleria Decades of Newe Worlde f. 186 To annoynt the place with oyle and scrape it with a rasoure.