Editing a Pipeline allows you to change the name, add required fields, add or update tags.
To edit a pipeline as an Admin, click the Manage Pipeline button in the top right of the Pipeline page.
Click on the pipeline you'd like to edit, and you will be able to change the name, add required fields, or add tags.
If you'd like to create a duplicate pipeline (settings only, no opportunities) you can click 'Clone Pipeline Settings'. If you'd like to delete, you can click the red 'Delete Pipeline' Button.
Note: you will lose all customizations and data from opportunities in your pipeline if you delete it!