If you’re having trouble installing the Office 2011 official install over the beta it could be because you can’t kill Sync Services Agent. It restarts itself constantly. This should kill it permanently and allow you to overwrite it.
$ cd /Applications/Microsoft Office 2011/Office/SyncServicesAgent.app/Contents/MacOS
$ mv SyncServicesAgent SyncServicesAgent.hold
$ killall SyncServicesAgent