Can't Delete Email Account

ERPNext
,
1

I’m trying to delete email account, but It said :
Cannot delete or cancel because Email Account xxxx@gmail.com is linked with Unhandled Email 3915f72ec3

2

You can disable it by unchecking Incoming and Outgoing email gateways.

3

I already uncheck the incoming and outgoing, and deleted the user who using that email. still same. whats next?