The pre-update checker might find some actions but it's not obvious that they can be selected directly by clicking on them from the pre-update checked window.
The button "select all" just does that, Inspector indicates that several Mono Scripts are selected but then their deletion is not accessible. Doing RMB in the Project window is risky because as nothing is actually selected there, it's impossible to know what will actually be deleted since Unity's UI does not adapt to the quantity of items selected as far as its menus go.
The only solution is to select them all with the checker's button, then go to Assets menu and select Delete. This will warn the user about the incoming deletion.
This is a dangerous operation, I admit I didn't know if Playmaker would then be able to update the instances of these soon-to-be deleted actions I use in FSMs, that is, make them point to the proper actions now which have become in-package default "official" actions.
I think a little clarification on this and a "delete (#) custom scripts" button might be good for users.