It is a very simple process on the Netcore email API account to change the registered email address. In order to do the same, you can follow the below steps,
1. Login to your Netcore email API account.
2. Click on the drop-down button available under your username on the top right corner and then on "Profile" as shown in below image,

3. Once done, you can click on the edit button as shown in the below image to update the registered email address of your Netcore email API account,

4. Once done, you shall receive a confirmation email on the new email address as a part of verification.
5. Click on the verification link in order to update the account with new email address.
In case if you have lost access of your account and hence cant change the email id, please reach out to your Netcore sales account manager with the same request or write to us at help@netcorecloud.com. Please note ONLY basis approval from your sales account manager, Netcore CPaaS Support team can get these changes implemented.