If you have access to cPanel, the process is simple.
If you don't have access to cPanel, just follow these steps:
1) Login to the Client Area.
2) Click "My Products & Services" on the right nav menu.
3) Click the icon for the hosting account in question.
4) Scroll down to the "Change Password" Section
5) Change your password. This will not work if you get a Brute Force error message on the cPanel login.
Also be sure to use a complex password.