First, you need to Login to your cPanel account.
Locate and click on the Email Accounts under the Emails section.
You will then be redirected to the Email Accounts where it will show you the list of email accounts you have in your server.
From there, click on “Password and Authentication” button for the email account you wish to change the password.
After that, you will be asked to enter your preferred password.
You can also use the “Generate” button to get a system generated password using your preferred password criteria as shown below.
Once done and created your new password, you may proceed to click on the “Change Password” button to save new password.