Email accounts might use up some of your iPhone's internal storage capacity. As a result, it is strongly advised that you erase or delete any unused or unnecessary email accounts from your device. Removing or deleting an email account is another possible solution to email problems such as being unable to send or receive emails for a specific email account.

1. From the Home screen, select Settings.
2. Select Accounts & Passwords.
3. Go to the Accounts section.
4. Select the email account you want to delete and press the Delete button.
5. Select Delete Account.
6. To confirm the operation, tap Delete from My iPhone.