From the User Monitoring - Attributes page, you can achieve the functionalities as follows:
View all of the attributes of the currently selected user from the user list on User Summary page
Add new attributes or delete existing ones.
Attributes are tags (key+value pairs) that can be assigned to a user either manually or programmatically. They are primarily (but not exclusively) used in defining and filtering segments for Promotions.
You can set your app to generate the user attributes dynamically at runtime via calling UpdateAttributes API of Player State service. Or, calling RemoveAttributes API to delete the specified user attributes. Check APIRef for more details.
The operations on this page are pretty simple and straightforward. To add a new Attribute simply click the plus icon in the top right next to the record count. A new input fieldset will append at the bottom of the list. The keys and values of any of the attributes can be edited directly in the list.
To delete an attribute click the trash icon to the right of it. None of these actions are applied until the Save button is pressed. That means by pressing Cancel you can revert any changes you made from the last time you saved.