No Worries..

Kat..

AVG will NOT detect the file/s, which you remove/delete from quarantine. Nor will removing the virus from quarantine and deleting it, reinfect your system. It's safe to do.

Unrelated to your question, but a couple of things you may want to note. When in quarantine, you want to make sure the file/s have been there a long enough period of time, to determine whether (or not) Webroot detected the file/s in error. In other words, that it wasn't a "false positive". In most cases it's not. Additionally, if your system has been running well with the virus in quarantine, it's also safe to remove.

As to your original question, I reiterate. Once it's removed from quarantine (and deleted) AVG will not detect it. Nor will the action of deleting the file/s reinfect your computer.

Good luck with the switch..
Carol