how would one go about deleting a selection?

Hold down Alt/Opt and add a Layer Mask

The usual behaviour when adding a layer mask is that only the selected area will be visible.

Adding the Alt/Opt key reverses that.  Non destructive. No brainer way to hide/delete a selected area.

​@Optimistic_Gazelleb470 if you are using the rectangle marquee tool and made an active selection, you can click anywhere on the artboard, image or pasteboard and click once, and the marquee selection will be deselected. As per ​@Claire H. , Command D (MAC) or Control D (PC) is a great keyboard shortcut to deselect as well. Or in the main menu - Select - Deselect
 

Instead of using the Eraser tool, I would use layer masks. They allow you to hide parts of an image without permanently deleting anything, making it much easier to make changes later if needed.

Hi ​@Optimistic_Gazelleb470 , here are the steps to delete selections from your image in Photoshop.

1. Select the Marquee Tool: Ensure you have the Rectangular or Elliptical Marquee tool selected in the toolbox.

2. Make a Selection: If you haven't already, create your rectangle or ellipse by dragging over the area you wish to select.

3. Delete the Selection:

   • Select the area you want deleted. Make sure it's not a smart object.

   • Press the Delete key on your keyboard. This will remove the content within the selected area without needing to use the brush or eraser tools.

   • If you want to deselect the area after deletion, you can do so by pressing Ctrl + D (or Cmd + D on a Mac).

4. Final Adjustments: If necessary, you can adjust the remaining image using other available tools that are not restricted.

By following these steps, you should be able to remove the selection effectively. You can also remove elements of an image using masking, a non-destructive way to remove parts of your image.
Please don't hesitate to reach out if you have any questions. Happy editing! ^CH