Remember since Android is fragmented, you must look around.
Here the email for the phone is under Settings, Accounts & Sync. On mine there's an check box to turn off sync. But that's not the only place the email can be hiding.
This phone has an Email app so I have open this app to change the email settings.
If I have installed Google's GMAIL app I have to open it and change as well.
I recently deleted a Google email account which was synced to my Android phone. I didn't realize I needed to shut off the sync before I deleted and now my phone won't stop telling me that it can't sign in. I've shut off everything in Android that I can find. I hope someone can help me with this annoying problem. Thanks.