What if I deleted your whole backlog? Would you freak out?
Oh, crap! You’ll have to try to put it back together from memory! What if you forget something? It might never get done!
Here’s the thing: If you can’t remember it, it’s probably not that important. If it is important, it’ll probably find its way into your attention again.
Put another way: If it goes away and nobody ever brings it up again, then nobody cared very much about it to begin with. It didn’t need to be in your backlog.
When I see teams with backlogs hundreds of stories long (always digital backlogs — hi, Jira), I want to delete them all and run away giggling. I’d be doing them a favor, refocusing them on what actually matters. But they probably wouldn’t see it that way.