https://www.gnu.org/licenses/gpl-faq...cePostedPublic
You can't modify and make the GPL clause disappear, as it as a derivative work (unless you try again, ie, start from scratch).
Also - it is very clearly a copy and paste - if not conforming to the terms of the license (AGPLv3) then it's just copyright infringement.
It's not much to ask that sites like this open source their code anyways.