Existing boundaries (i.e. External, Material, Water Table, Piezometric Line or Tension Crack), can be deleted, using the Delete Boundary option. Delete Boundary is available in the menu, toolbar, or as a right-click option for individual boundaries.
To delete boundaries:
Select Delete Boundary from the toolbar or the Edit sub-menu of the Boundaries menu.
Use the mouse to select the boundaries you would like to delete.
When you are finished selecting, press Enter or right-click and select Done Selection, and the boundaries you selected will be deleted. (See the note below about deleting the External Boundary).
Right Click Shortcut
The Right mouse button can be used as a shortcut to delete individual boundaries. To do this:
Locate the cursor over a boundary that you wish to delete (e.g. a Material Boundary, or a Water Table).
Click the RIGHT mouse button, and the boundary will be "selected".
A popup menu will appear, from which you can select the Delete Boundary option.
Select Delete Boundary to delete the boundary.
Deleting the External Boundary
Although you are allowed to delete the External Boundary, it is important to note that if you delete the External Boundary, YOUR ENTIRE MODEL WILL BE DELETED!!! Since all other modeling options require that the External Boundary exists before other entities can be created, all entities must therefore be deleted when the External Boundary is deleted. This includes:
All boundaries (Material, Water Table, Piezo Line, Tension Crack)
All loads (Line, Distributed)
All surface objects (e.g. slip center grids, single surfaces, search objects)
You will however, first see a warning dialog, if you try to delete the External Boundary. If you selected the External Boundary by accident, then select No in the warning dialog.