Step 1 - Setup A New Multiple Credential
First, login to your account with your primary credentials and head over to the Multiple User Credentials page. Create a new set of credentials that have (at minimum) access to send Mail.
Step 2 - Update Your Integration With The New Credentials
Now that you have a new set of credentials, go into your existing system and update your integration or code to use the new Multiple Credential username and password. Run a few tests to ensure that mail continues to flow as expected.
Step 3 - Deploy The Changes
Now that your integration has the new credentials, go ahead and deploy your changes into production.
Step 4 - Update The Original Credentials
Finally, once your integration is fully using your new credentials, you can go and reset your password for your original credentials without interrupting your mail flow.
Step 5 (Optional)
If you’d like, once your original credentials have been changed, you can then go and update your integration again to use the primary username and new password. Once you deploy those changes, you can go back and delete the alternate credentials you created in Step 1.
Good luck, and don’t hesitate to contact Support if you have any questions about the process!