To access the working copy, click on the "Working Copies" tab of the vocabulary and then click on the name of the working copy you wish to edit.

 

You will be directed to the working copy's view.  Click on the Edit Working Copy link to make your changes.

The vocabulary will open.  The vocabulary editor has three panels:

Editing a concept

To edit a concept, locate it using either the tree or by searching.

Click on the Edit button located at the bottom of the concept details panel.  The concept details panel will change to allow you to edit the concept.

When you have made your changes click the Save Changes button.

Deleting a concept

To delete a concept, click on the "cog" icon at the bottom of the concept details panel and choose "Delete" from the popup menu.

You will be asked to confirm the deletion.