What happens if I delete an email account on my iPhone?

Deleting an Email Account Removes All Emails From the iPhone. IMAP, POP, and Exchange as well as accounts configured with automatic settings (such as Gmail, Outlook.com, and iCloud Mail) will have all content wiped from your iPhone — iOS Mail will remove all emails and folders listed and created under the account.
For More Information Please Refer:
You May Also Like to Read:
How to delete app profile?