I presume that you don't have a storage unit for other stuff you can store them in.
In the old days you could give them away to kids to use as toys, but nowadays everybody is worried about things like swallowing small parts so toys have to be kid-proofed.
You may be able to find a library that would like a display, but they usually want you to take them back after a while for another display, so that's not a permanent solution.
Are there any model or toy swap meets held near where you live? I know I buy used and partially finished models to raid them for parts and kit bashing. That's probably the most useful thing you can do with them.
When I had to leave models behind like when I was in the service I would take good photos for my memories and dump them. So maybe that's the best you can do.
When I was a kid I would dispose of unwanted models by BB gun, lighter fluid and sinking in puddles, but I'm too mature for that now. (OK maybe mature is the wrong word, I'm too old). Nowadays I have enough room that I don't have to toss anything.