Any citric based cleaner will remove the wax.
A Brass brush is used before you apply wax. this brush removes all dirt and crap from the base so that way you can apply wax on a clean surface.
If u really want to clean out old wax then do the hot scrape method.
Apply wax, heat it in with an iron, and while the wax is still warm and moldy, immediately scrape it off. The warm wax will stick to the old wax and when u scrape it, the warm wax will pull out the old wax and therefore it cleans out the pores