M. To delete an opening

Use this procedure to delete an interior contour or hole from the shape.

Inner contours must be previously specified for the tools used to be active.

Select either

Edit > Delete internal contour

or
the Delete tool
Click anywhere inside the contour or hole you want to remove. The internal contour is removed from the shape.
Exit the delete contour mode by either:

repeating step one

or
selecting some other drawing mode