Very cumbersome, but using the "big sledgehammer" approach, you could do this if it's a XL 2007+ file:
=SUBSTITUTE(SUBSTITUTE(SUBSTITUTE( SUBSTITUTE( SUBSTITUTE( SUBSTITUTE( SUBSTITUTE( SUBSTITUTE( SUBSTITUTE( SUBSTITUTE(A1,"1",""),"2",""), "3",""),"4",""),"5",""), "6",""),"7",""),"8",""),"9",""),"0","")