You can technically put them into storage with the storage feature; the player character is removed from the game and can be brought back out whenever you want

I think you'd need to bring it back out before the player reconnects however as otherwise they'd spawn in with a fresh version of their character, and when you bring the old one out you'd end up with 2

(i guess you could just kill the fresh one with respawning turned off to solve that problem but... yeah)

I didn't develop that feature so i don't know all the inner workings of it, but afaik it works well enough

by storage i meant the "reserve" feature