trouble changing my email back to the original email

@Zemlay Most likely that original email is still in use on another account. I would try using the https://zoom.us/forgot_password with your original email to see if you can login after going through the process. If you would have originally logged in via gmail or any other method, try that method first and then you can terminate that account. 
Deleting-or-terminating-your-account 

After terminating you can go to the account you are wanting to change the email from, and then use your original email needed. 

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