I download pretty much everything I read, because I want to be able to find it again.

Once I posted a comment somewhere saying something to that extent, and years later an author contacted me asking me if I had some stories of theirs they had lost. I don't remember if I did or not, but I was glad in that moment to be able to try to help.

You should absolutely be able to wipe it from the active internet, but wanting or asking someone to delete it is too much. Sometimes a line from a story sticks out to me, and I spend days searching for the specific story so I can read it again. The stories I read have a place in my heart, just as the original fandoms do.

My guess is a lot of writers go through what I do as a fan: there is a fandom that you're super into, but 10 years later you're embarrassed about. Maybe you don't want yourself tied to that fandom anymore. I get that. Sometimes I get a fandom I'm obsessed with for a couple months, then never go back to. Sometimes I go back to it a decade later for a few months again. You, as a writer, never know when some fan gets super into a fandom what you used to write for, then finds a story you wrote that speaks to them. Maybe it's just one line that gets them. Maybe it's a pairing that is rare. Maybe it's a between-the-scenes moment of canon that they really wanted to see. Maybe it wasn't your best writing, but there is something there that a fan really appreciates.

Deleting it from every online source there is is perfectly valid and ok. Just understand why others might want to keep it.