Why do I have an Xfinity account (through Xfinity) and also a (Comcast account) through "web.mail.comcast.net/zimbra/mail"?
Unsure what one I should delete?
I have recently synced my Gmail account with Comcast, should I have done this?
Where are you seeing "Zimbra"? That was the old email software. You should now be on Appsuite. Do you not see that in the URL when you are in the email?