1- To Change your password via webmail, go to your webmail URL.
Example: http://webmail.yourdomain.com

2- Enter your full email address and current password and click the login button:

3- click on the drop down menu:

4- Click on password & Security:

5- Enter New password twice to confirm , click save button and you are done.

6- You can logout or choose a webmail application to use your email.
If you need further help,please send an email to support or open a support ticket.
Websien Support