A CTRL-Z will UNDO changes as most Windows programs do. Within the PowerHome Explorer, an F10 will UNDO everything done on the current detail window. Once you leave a detail window (or refresh/save with F5), the changes are permanent and F10 will have no effect. A CTRL-Y will REDO actions, as with most Windows programs.
When you delete a macro line, two things happen...
F10 will “Undo All” (up to the last save).
There is also a CTRL-Y for redo.
Thus if you're working on a screen and have made multiple changes, a single F10 will revert you back to where you were when you first entered the screen.
You can also ctrl-z your way back to this point. But if you hit F5 (Save/Refresh) or navigate to a different Explorer detail screen, your changes are saved to the database and are permanent.
These 3 options are also available and shown on the PH Explorer toolbar (last 3 buttons) and the "Edit" menu.