This will completely delete an email address and email account from the Mac Mail App, including all settings for the email account, and removing all associated emails from the Mail app in Mac OS X.
This procedure is applicable for removing email accounts from your iOS devices (iPhone, iPad, etc.) running iOS 6 or higher.
Go to your iPhone or iPad’s Settings > scroll down and tap Accounts & Passwords > Add Account. Note: If you’re on iOS 10, go to Mail > Accounts >Add Account. Select Exchange. Enter your Office 365 or Exchange email address and a description of your account. Tap Next. Note: For example, @yourdomain.com, @domain.onmicrosoft.com, or @schoolname.edu. Tap Sign In. Enter the password associated with your email account. Tap Sign in. The Mail app […]
In the Office 365 admin center, you can add a new credit card or bank account, update an existing credit card or bank account, or delete a credit card or bank account that you no longer use. You can also change the credit card or bank account that you’re using to pay for a subscription.