If you use the Joomla forum extension Kunena, here's an easy way to remove the obnoxious footer backlink.

Joomla extensions are required to be licensed under the GPL. Most people, incluing most developers don't fully understand the GPL.

It's quite simple in terms of what you are premitted to do with GPL licensed software.

• You are free to edit the sotware in any way you wish.
• You must keep the copyright notices that are in the PHP files.

So yes, you can delete the footer link, even though the original creator may not like it, you are perfectly within your legal rights. Sure, developers should receive credit and/or compensation for their work but there are plenty of other avenues to do so without smearing a link everywhere. Backlinks may have been useful 5 years ago but things change and those links only effect SEO in a negative way.

Ok, enough rambling and on to removing that damn link...

This is valid as of Kunena 5.0.7.

Open up an FTP program and find your way to /libraries/kunena/controller/application/display.php

On line #287 all you need to do is change the 1 to a 0.

Change

if ($this->config->get('credits', 1))

To

if ($this->config->get('credits', 0))

Save the file and check your site. The backlink should now be gone.

Edit: As of Kunena 5.0.8 the line number is #290.

Edit: As of Kunena 5.0.10 the line number is #299.

Edit: As of Kunena 5.1.0 the line numbners are #405 and #406

Edit: As of Kunena 5.1.10 the line numbers are #406 and #409 change:

display: block !important;

To

display: none !important;