On occasion, a user may wish to use a program that is part of another distro packaging.
To install that software, the user may add that distro repository to their sources.
You must remove that repository once the software has been installed.
Some distros use different versions of packages over-all. If you keep the repository, the next time you run updates, you may change or replace Zorin Packages or in a worst case scenario, break Zorin OS and have to reinstall.
Always remember: Remove any other distro Repository once you have used it.