1. MDTools Library Manager ribbon
> Materials
> Manage Materials
The Manage Materials dialog displays.
2. Select the material you want to delete.
3. Click Delete to delete the material along with all its contents.
A message box displays.
4. Check the material name mentioned in the message box to make sure that the correct material is selected for deletion.
5. Click Yes to delete the material.
CAUTION!
A material, once deleted, cannot be recovered.