At node level, you can't change the existing property name but you can delete it and add a new name with the same details at the node level.
But if this name is a dialog property, please change it at the dialog level of that property in the respective component.
In the above screen shot, you are referring to a content fragment, which is a ootb component. In order to customise it you'll have to create a custom component which acts like a CF or overlay/extend the CF.
Thank you,
Sravan