Navigate to "My Maps" and select the map you want to edit.

Click on the boundary or line you want to edit.

Click on the "Trim Boundary" tool under the boundary menu.

Go the area you are trying to erase anchor points. Then click the map to create a start drawing a shape around the problem area.

Tip: If you mess up on any of your clicks there is an undo button in the menu in the upper right hand corner.

Double-click to end the drawing and delete the anchor points inside your area.

Using the trim boundary tool (desktop)