The Powered By jPFChat line that appears at the bottom of the jPFChat window can be removed by purchasing a license to do so.   Once you buy the license, you may alter the setting in the jPFChat back end (license tab) to turn OFF the Powered By display (v2 only).

To remove the Powered By from jPFChat v1.x.x

You have two choices... upgrade to v2... (highly recommended) 

Open the components/com_jpfchat/jpfchat.php file in your favorite text editor.  Inside, near the bottom of the file, you'll find some comments about removing the lines that display the Powered By line.    Delete them.

To remove the Powered By from jPFChat v2.x.x

Open the jPFChat component settings in the Joomla back-end.   Click the jPFChat License tab.  There, you'll see an option to remove the Powered By and phpFreeChat logo (see the warning below).

NOTE:   The phpFreeChat logo... on the main chat window screen is DIFFERENT and SEPARATE than the jPFChat license.  

We didn't write phpFreeChat.  We wrote the jPFChat script, that takes phpFreeChat and integrates it into Joomla.   If you want to remove the phpFreeChat logo... then you'll need to buy THAT license separately from the phpFreeChat website.