Remove Lasso tools: control points
When using either the Polygonal Lasso or the Magnetic Lasso tools (both nested under the Lasso tool [L]), you can remove control points in the order in which they were put down by backtracking along the selection path and pressing the Delete (PC: Backspace) key for each point. The Magnetic Lasso tool may try to add new points as you back up; just delete them until you get back to where you need to be.