A rolling library ladder is beautiful but fussy: it hangs from a track and rolls on hooked wheels. Detach it cleanly and keep the rail hardware together, since that track is what makes it work.
Pro tip: Measure and photograph the exact height and standoff distance of the rail before removal so the ladder rolls smoothly after reinstall.
Watch out: Do not force the top wheels off a closed track; you can bend the hooks or gouge the rail. Remove the end stop instead.