Does anyone know if there is a way to remove this annoying popup AFTER a project has been created?
Keep getting a popup in the IDE every time I Play
Are you trying to use a project for which you’re not a member? 
I’ve never seen or heard of that.
I imagine either fix your membership, if you should be a member, or possibly disable Unity services for it (if that’s possible). Honestly, not sure.
Yes, if your project is using stuff like unity analytics and it was created under one account, but then you log into Unity under another account and open the same project, you’ll get that. Happens to me when I use the wrong account for work projects at home.
It may happen if you open a project in offline mode as well. You either need to use the same account, have your other email added to the project, or when you create a project, I think if you disable the analytics that is the one service that is normally on for projects.