Erase them from the Internet
OK, I may not be able to erase them from the whole Internet, but I can erase them from my bit of it:
> ian@desk:~$ ssh root@nameserver
> No mail.
> Last login: Thu Sep 2 19:52:08 2021 from desk
> 20:01:25 up 16 days, 7:57, 1 user, load average: 1.54, 0.56, 0.20
> root@nameserver:~# cd /etc/bind
> root@nameserver:/etc/bind# ed policy.zone
> /insert new records here/a
> teespring.com CNAME .
> *.teespring.com CNAME .
> root@nameserver:/etc/bind# make
> Zone file policy.zone changed.
> Updating serial number on policy.zone.
> Notifying nameserver to use updated zone policy.zone.
> root@nameserver:/etc/bind# exit
There, done. The delights of running your own DNS firewall, you can blackhole any domain you like.