There are a few ways to deselect parts of a selection in Photoshop. One way is to use the command “Command-D” (or “Cmd-D”) to select all of the elements in the selection, and then use the “Option-click” or “Option-drag” keyboard shortcut to deselect just one element. Another way is to use the “Command-E” (or “Cmd-E”) keyboard shortcut to select all of the elements in the selection, and then use the “Option-click” or “Option-drag” keyboard shortcut to deselect just one element.