In the User Administration page, find the user that you'd like to edit then click on "view" as shown below
The user details will pop up in the middle of the screen, select "Edit" , a form on the left of the screen will appear. Make your changes then hit "Save Changes" at the bottom left of the form. You can also click on "cancel" if you do not want to make any changes
If you'd like to delete the selected user, hit "Delete User" at the bottom right of the form