Autocad hatch generate boundary polyline

You have a drawing that contains hatches with boundaries, and you want to recreate the boundaries or remove a section of the hatch pattern.

To recreate a hatch boundary

Enter HATCHEDIT on the command line.
Select the hatch.
In the Hatch Edit dialog box, click Recreate Boundary.
When you see the prompt “Enter type boundary object”, enter P for polyline or R for region.
When prompted, choose whether or not to associate the hatch with the new boundary.