m4tt0 Beginner

wipefs -a <device>

http://manpages.courier-mta.org/htmlman8/wipefs.8.html

might do the job. Either it is faster (never used it myself) or you could run it in background or using screen.
You need to do in CLI. Not possible from GUI.

Agreed. Just saved me from waiting days as well... Many thanks, macom !