Syncing and deleting categories in Outlook?
You can delete the category by finding its ID and using the command:

delete category id &lt;#&gt;

So something like this works fine:

tell application "Microsoft Outlook"
    set badCategory to "foo"
    set allCategories to every category
    repeat with varCategory in allCategories
        if name of varCategory is badCategory then
            delete category id of varCategory
            log "name = " &amp; name of aTag as string
            log "id = " &amp; id of aTag as string
            log "deleting it!"
            exit repeat
        end if
    end repeat
end tell