Hello Reema
Once you create a CR with edition and approve it, you can't delete that edition using NWBC - i.e delete edition option.
You can only release the edition using edition monitor and then create a fresh edition.
Try it in your system. Create a dummy edition and approve 1 CR. Try to delete it through NWBC - Edition monitor - delete option. The delete option itself is not visible in this case.
Kiran