v.v...I completely misunderstood/misread/overlooked that delete option...would have made my life so much easier..sigh.
Anyway, Windows search ...pfffffffft.
cmd prompt
DEL /S C:\Users\Username\Calibre Library\*.pdf
....I think mine works better.
By the way.... anyone having problems with the program hanging and taking its sweet ass time during converts/deletes? I'm sitting on a quad code with 8gb of ram, I cant really fathom why it is hanging so much and taking so long....