[xenomachina]

There are at least a couple of ways of indicating that an entry should be deleted in RSS and Atom, but they don't seem to be well-supported.

This blog post mentions a couple: https://oleb.net/blog/2015/11/rss-feed-item-deletions/

I vaguely recall that Microsoft also had some proposed mechanism, but I can no longer find any trace of it. I doubt anything supports it.