From the Home screen tap Settings
On the Settings screen, scroll down until you find Passwords & Accounts
Tap on Passwords & Accounts
In the Accounts section, locate the account you wish to remove. There may be several listed, tap on the account you want to delete.
To delete the account, tap on Delete Account
You will be asked to confirm that you want to delete the account.
The account will now be deleted.
You will be returned to the Accounts page.