Here's how to use the cPanel File Manager to edit the contents of any text-based files in your Linux Hosting account.

From your client area go to:

Services -> My Services -> click on the green "Active" button -> Login to cPanel/Control Panel

In the top left-hand corner of the account Dashboard, select File Manager.

In the cPanel File Manager, use the directory tree to browse to the file you want to edit. Right-click the file and select Edit.

(Optional):

Select any encoding options you want to use and then select Edit. Edit your file, and then select Save Changes. Select Close to go back to the main File Manager page.

More info: For more help, see the cPanel documentation for File Manager.