The Polygonal Selection (or the polygonal lasso) tool lets you make straight-edged, polygonal selections.
Choose the Polygonal Selection tool by doing one of the following:
Tip: You can cycle through Magnetic, Free, and Polygonal selection tools by pressing Shift ⇧ + L on your keyboard.
Click in your image to add straight selection lines to make your selection.
Click the start of the selection to finish it. Alternatively, double-click anywhere in your image or press the Return ↵ key.