One of the reasons the pen tool is so powerful is because shapes are fully editable during and after their creation. Start creating a shape on the stage by clicking any number of points. Return to one of the existing points and place the cursor over it; notice the “minus” sign that appears under the cursor. Click the point to remove it. Illustrator automatically connects the remaining points, allowing you to adjust the shape as needed.
To add to a shape, you must first create new points on the shape lines and then adjust the angles that lead up to that point. Create a shape on the stage. To add a point, select the “add anchor point” tool, which is in the pen tool set (keyboard shortcut “+”). Click on any line or path of your shape, and a blue box will show you have added a point. Next, select the “direct selection tool” which is the white arrow on the toolbar (keyboard shortcut “a”). Click and hold on one of the points you have created and drag the mouse to adjust the shape.
To delete an anchor point in an existing shape, select the “delete anchor point” tool, which is part of the pen tool set. Click on any point of a shape, and it will removed as it was when we removed points earlier.