1) To edit an existing PCB Lib (footprint/package) first, find it using the SHIFT+F search then left-click on the desired PCB footprint in the list that appears to select it and to check the preview.
2) Next, right-click on it and click on Clone (or click on More > Clone).
3) Rename the copy:
4) Then click OK to save it.
5) Find the renamed copy using the SHIFT+F search then left-click on it in the list to select it.
6) Next, click on Edit.
The PCB Lib will open the footprint in the PCB Libs editor:
7) Make whatever changes required then Save it.
8) Then go to:
Document > EasyEDA Source...
to open the EasyEDA Source Editor window and edit a new name for the contributor and enter the new package name between the double quotes (" ") in the fields outlined in red:
Do not change anything else!
9) Click Apply and note the changes to the Contributor and Package fields:
If the edited PCB Lib is correct then Save the edited PCB Lib.
10) Find the renamed copy again using the SHIFT+F search then left-click on it in the list to select it.
11) Wait a second or so and then right-click on it and select Modify
The edited footprint will appear to the creator in My Parts:
It can also be found by everyone using the SHIFT+F search under User Contributions but for anyone but the creator to use it, they must first left-click to select it and see the preview and then right-click on it and click Add Favorite: