Why do I have a gezakovacs' PPA?

When I do an update I get this output:

Hit:1 http://ppa.launchpad.net/gezakovacs/ppa/ubuntu xenial InRelease
Hit:2 https://mirror.fsf.org/trisquel flidas InRelease
Hit:3 https://mirror.fsf.org/trisquel flidas-security InRelease
Hit:4 https://mirror.fsf.org/trisquel flidas-updates InRelease
Reading package lists... Done
Building dependency tree
Reading state information... Done
All packages are up to date.

I wonder why is that first PPA on my system, I've never added it. I also want to say that I can't delete it with ppa-purge.

Someone could explain?