Removing old wax before buffing/rewaxing

[jjns]

If you rinse with clean water and it beads, there is wax, if it sheets, it is clean.

[SJ34]

When water no longer beads wax is gone.

[Nazdrowie]

You could use the "wax stripper - cleaner" that is used by autobody repair shops, just prior to painting a car. I bought mine from a local auto body paint supplier (not a body repair shop). I believe the 1 litre bottle cost $8.00. You just have to wipe it on and that's it!
Good Luck
Domer