closed, moved, burned down. . .
E-- now that KOTR has turned 4, I notice more and more info has changed. While removing an area or gym that has closed/changed etc might not be wise (Korean websites list gyms closed since 1999 and "new" foreigners might get confused if the post is removed altogether; climbing areas stand a chance of being reopened. . .), I've seen websites have "closed" "moved" etc options. In some cases, like the YDS sign at Maisan that hasn't been there for years, it might be better to move so people won't look for the sign (as the climbing is still there!)
In some cases, it's hard to track down the original posters, and the comments get so long that some might not read through them (i.e. I'd have no problem if you remove my dated train schedules to Kanhyon, as they've changed and I've posted the new ones. . .)
It's a lot of cleaning/amending, but it might make some of the places a bit easier to find. . . maybe even make it so anyone could flag a change?
"If you can't do something well, you might as well learn to enjoy doing it poorly."
-- from a de-motivational poster, but I find it oddly liberating