AzDude is right, but if you're only wanting to use WB occasionally, you might be better off to just apply the Default theme (1st theme) which also unloads WB, and it won't load again at startup until you apply another WB theme.  After you use the WB theme for awhile and want to go back to the default, apply the default before you logoff.

I guess it depends on if you want a WB theme most of the time or the default theme most of the time.   

Or you can permanently turn it off by way of disable its service in the system.