Updating, would be via new version of tiara.
Which may or may not be released on time.
To manually edit it yourself, you'll need to open it in notepad, and edit it.
In my guide, I wrote a section for editing the prop xml, it's not THAT much different...
It's the basics for almost every xml ever.
Take a look at that in my guide, then look at this xml... If you're still lost, simply delete it or wait for a new tiara.
If I have some more free time I may write a guide for itemdb, but until then... Either you get it or you don't lol