From the User Monitoring - Inventory page, you can achieve the functionalities as follows:
View the list of the items that owned by the currently selected user with item-id searching, and sorted list by various fields
View the details of each item
Switch to item catalog design page
Delete item individually
As for the details of how to create and retrieve items through APIs, refer to the user-item APIs docs here.
The following screen will be seen when browsing to Monitoring | User Monitoring | Inventory page, which will display the list of the items owned by this user.
Click the Item Id column of each entry (or click the View option from the Actions drop-down column), it will open this item summary page.
Item summary page:
Click the Definition Id column of each entry, it will select this item catalog and redirect you to the item management catalog page.
To search for an individual item from the inventory list, you can just enter the item Id into the search bar on the upper-left corner of the list and hit enter, it will return the specified item. (To clear this searching result, just simply clear the search field input and hit enter again.)
You can delete a user-item by clicking the Delete option from the Actions drop-down column, and confirm the delete operation from the pop-up window.