how to disable open last project on launch

I had created a basic project with 15 beta and I had also enabled the pref for automatically opening the last project on launch. Upon relaunching though it seems to be hanging (app not responding) as it opens into that project (so I'm not able to do anything with the beta at the moment) - is there a pref I can trash to prevent it from opening the last project (or a modifier key while launching) etc. ? thanks for any suggestions.
Mac OS 10.13.4
Mac OS 10.13.4