A 9 volt battery already exists in the core parts library. Actually 7 of them, plus a battery holder.
In the “Parts” window, “CORE” bin, “Power” section, drag the “Battery” part to your sketch (any view). It looks like a pair of AA batteries in a holder. Make sure the part is selected in the view, then in the “Inspector” window, change the “voltage” property to “9V”.
Many related parts can be found that way. An arbitrary individual part from a “family” of parts can be located in the parts window, then Inspector can be used to switch between the members of that family. But only have the part has been added to the sketch. Instector is only effective for making changes after the part has been placed. When hovering over (or selecting) a part in the Parts window, Inspector provides a read only view of the part information, including the available properties that could be manipulated once it is in the sketch.
One reason for Fritzing to “stack” parts that way, is to keep the number of selectible parts to a «somewhat» manageable count (in the Parts window), while still providing access to the full set actually stored in the library. Only a single part from each “family” needs to be shown in the Parts windows. A quick check shows there are currently 1723 parts in the base library on my system.
Using “search” (magnifying glass icon) in the parts window can narrow down the selection, and shows parts from any of the bins. A search for “9v” provides several options, most of which should be available by changing property values as described above. That only works though when there are properties that exist in the current part, but with a value that is different in one of the other parts. For this case, there are actually 3 groups. One with different “variant” property values (standard pads, or large pads), another with different “test scenario” property values, and finally a sparkfun battery holder, which is actually from a different “family”.
The 2 groups in the same family should really be cleaned up in the parts library. adding “variant = none” to the one group, and “test scenario = none” to the other would allow switching between any of them using Inspector. I do not know the purpose of the test scenarios.