Basic computer and email issues

I have a few little nagging issues with my email and computer. When I boot up my computer I get some pop-ups that are remanants of some program I deleted, but I don't know how to get rid of them.

When I am using my laptop I can access both my work and personal email through outlook. On my phone I cannot get my work email to connect, which also means my work calendar doesn't populate on my phone.

I also have several ...onmicrosoft.com accounts and I don't know which is which and how to kill the ones that I don't need. At one time I was trying to upgrade to Microsoft 365 pro, but it became a nightmare because my website is throuh a godaddy subcontractor. Finally I just dropped the whole 365 Pro and kept the family version. Anyway...in doing all that I created extra "onmicrosoft.com" accounts that I don't need.

I know there's another little issue or two that I can't think of right now.