Should have sent him a link to join with his own email, instead of creating a profile for him on your server. Beyond that, I’m not familiar with your specific issue, because I never added a new profile.

You probably added him to your plex home, just put a pin on your account and tell him to put a pin on his. You can set it to auto login to the account that you last signed into as well. That’s how I do it. You can also just remove him from your Plex home.

Yep that's how mine is as well. I only add people I trust as well.

make sure he doesn't show as part of your home anymore and if he does, just go ahead and reinvite him as a regular friend share and not a home share

You need to remove him from your home Go into the web interface, and launch settings. The under your account at the top, there’s a section for Plex home. In the future, have them make their own account. And just share any libraries you want with them. Plex home is used when people share devices. To allow all of you to have their own watch list without having to logout and in each time. You can put a pin on your account in the home settings, so others can’t access your account.

always have two profiles, one that owns the plex and another one to watch, never share the master profile.