Help starting from scratch on OSX

Hi there
I've been running plex for a few years now and very happy. The install at mum & dad's works a dream, but at home it's been a little buggy - frequent crashes of the PHT etc. Tried a bunch of troubleshooting, reinstalled PHT but no luck, so I figured no big deal to start from scratch with both PMS & PHT. I followed the instructions for a complete uninstall - deleted all the app support files, caches, preferences etc. Emptied recycling, restarted, ran a search for anything with "plex" in it, including system files. Seemed to be clear of all Plex related info.
I've reinstalled the PMS, and the first thing it's done - ask me to log into my account.
Prior to deleting, I deleted the server from my account & signed out etc. This is the second time I've tried it so was doubly sure to remove it. Any clues as to how it's remembering that it's linked to an account already? First time around I just signed in, but the crashing from the prior install was still happening, so I was hoping to start a new account altogether to try and leave the issues behind!
Running both PMS & PHT on Mac Mini, OSX 10.11.15.
Thanks in advance!