The second method is to select the Mode in the Tool Options and then click the mouse around the edge of the area to be deleted. You will know you are in this mode when a minus sign ( -) appears in the cursor. This switches to the Subtract from Selection mode. The first is to hold down the Option/Alt key and drag around the hole. You have a couple of choices around accomplishing this task. Subtracting Areas: You have selected the edge of a doughnut but you need to remove the doughnut hole from the selection.Releasing the Option/Alt key after switching tools returns back to the Magnetic Lasso. If you release the mouse after clicking on the edge, you will switch to the Polygon Lasso tool. If you continue to drag you will automatically switch. Switch Between Lasso Tools: Press the Option/Alt key and click on the edge.Remove an Anchor Point: Press the Delete or Backspace key to clear the last anchor that Photoshop put down.
All you are doing is enlarging the edge detection area.
You can make it larger or smaller by pressing the keys. Width: This is the width of the circle when the Caps Lock key is pressed.If you are new to this try and keep the value between 0 and 5. This is how one softens the edge of a selection. Feather: The value is the distance the vignette or blurred edge of the selection will extend from the edge of the selection.Once you have selected the Magnetic Lasso, the Tool Options will change.