Note: This action doesn’t cancel the email account; it just removes the access to the e-mail account from the native mail client on your mobile Apple device (iPhone / iPad) or Android device (such as a Google or Samsung branded smartphone or tablet).
If you have an Apple iOS device such as an iPhone or iPad, click the following link:
Removing Email Accounts from Apple Devices (see section "Delete an Email Account")
If you have an Android-based device (i.e. Google or Samsung smartphone or tablet), click the following link: