This procedure is applicable for iOS devices (iPhone, iPad, etc.) running iOS 11 or higher. The screenshots shown below were taken from an iPhone 8 running iOS 11.3.1. Other devices will be similar. To delete an Exchange or other email account on an iOS device, perform the following:
1. From the home screen, tap Settings.
2. Tap Accounts & Passwords.
3. Tap the Exchange or other email account to remove.
4. Scroll down and tap Delete Account.
5. Tap Delete from My iPhone to confirm. Note that other types of iOS devices will display similar confirmation notices.
6. If you intend to reconfigure the same email address, we recommend that you restart the iOS device before attempting the reconfiguration. Hold the lock button down and slide the dial right to power off the device. The power up the device and proceed to the article listed below.
To reconfigure your iOS device for Exchange 2013, refer to the following article for setup procedures: