The last paragraph currently reads: If you would ever like to remove an address you have previously validated from the list of previously validated email addresses on your account (perhaps because you no longer use the address or it is no longer valid), you can visit http://www.livejournal.com/tools/emailmanage.bml
To my knowledge (and experimentation a few days ago), this isn't correct. You can't remove older email addresses on your account-- unless you're validated as a still-older one. That is, if you create the account with A (validated), change to B and validate, and then change to C and validate, you cannot remove either A or B. If you have access to A, you can remove B by switching to A, validating, removing B, and (if you want to) switching back to C.
The email management tool was, I think, created for situations where user X (with address A) creats an account; user Y (with address B) sneaks in and adds B to the list of email addresses; X regains control, and wishes to keep Y from being able to simply request a password reminder. (...and Y can't remove X's address, which means that, in theory, X can always regain control, provided they can access their email account.) It's a necessary security limitation, but it does mean that people can't remove older, dead addresses, because there's no way to ensure that they're them.
The wording of the FAQ, though, implies that you can remove previous addresses. It should be clarified; I'm too dead to think of good wording right now, but, yeah, clarification would be good.
Unless, of course, the situation's changed in the last few days :)