This isn't a legal question, I'm just interested in philosophical standpoints on this: do you think artists should be allowed to erase all traces of their own art from the internet?
e621 seemed to take a hands-off approach on this back in the day, before the legal implications became prohibitive.
There has been an interesting divergence in philosophy of various furry art archives since then.
At one end of the spectrum you have modern e6, which has a user friendly way for artists to take down all of their content without sending a DMCA request.
In the middle you have the various boorus which don't have an easy way to take down content, but will respond to a properly formatted and itemized DMCA request.
At the most extreme opposite end, you have the Permanent Booru which not only does not respond to any takedown requests, but makes the underlying data that it mirrors from other sites functionally immutable using IPFS (a side effect of all this mirroring being that the tagging system is kind of a mess, being derived from multiple sites)