How to configure the Apple Mail?

To delete an existing account:

1. Select System Preferences
   
2. Select Internet Accounts
3. Highlight the account to be remove and click the minus button and click OK to Delete it

To add your Exchange Online email account:

1. Select System Preferences
2. Select Internet Accounts
3. Select Exchange
4. Enter your Name and Email Address and to Sign in
5. Click Sign in
6. Enter your password to Sign In
7. Approve the 2FA login request 
8. Accept the Permissions requested
9. Click Done after the account has been added