The Ownership Thief item is a tool used to change the owner of a screen. This is an admin tool that cannot be crafted. Also note that the item can be disabled in the configuration file.
How to use
In creative, right-click on the target screen using the item in your main hand. When the screen is selected, anyone can use the item to take ownership of the screen. To do that, just use the item by right-clicking it anywhere.