removing the plist should fix that, that's where recent items are stored, they are not managed globally. (though they do use a standardized structure)
My directions above list the process required to get aound cfprefsd's pesky "being helpful" caching of preferences. Basically when an app tries to load a pref, the daemon opens it on the app's behalf, and caches it. It does this because some apps are continuously reading/writing to their prefs file when they don't need to be. It buffers this and dumps it when the app exits. Even if the app crashes, it gets written because it's the daemon doing the writing. (it also reduces disk read/write power requirements and also helps avoid flash cell wear) But if you open the app, verify the issue, close the app, modify the pref, and reopen the app, it will pull the cached data because cfprefsd can hold onto it and overwrite the file (and your changes / deletion) minutes or even hours later.
The best way to avoid that is to not launch the app after reboot. trash the pref before the daemon gets wind of it being accessed. You can kill the daemon but I've had mixed success with that approach. (as have others) Note that if you use the "approved" access methods (defaults write) it goes through the daemon. But that's not useful for WIPING the prefs file.
