Proper way to clean before re configuring

Hi

I just wonder which is the proper way to clean a qt build before running configure with some new options. Say that I have a normal build but then I want to remove phonon support with -no-phonon. So I want to rerun configure and then nmake again.

What do I need to do before reconfiguring. I tried to run nmake confclean and it seems to delete a lot of stuff but then when I rerun configure I started to get build errors.

Which are the proper steps to take when changing the configuration for my qt build?

Thanks