Undoing or redoing changes in project explorer
How to undo the most recent edit action in the view containing the projects/resources:
In menu Edit, select Undo.
Repeat the last step as often as you need to reverse editing actions.
How to redo the most recent undone edit action in the view containing the projects/resources:
In menu Edit, select Redo.
Repeat the last step as often as you need to re-apply editing actions that have been reversed by Undo.