In order to edit or a delete a Menu link,  you will need to navigate to the Edit Menu screen.   While logged in to your website, go to Manage, then Structure, and choose Menus from the options listed.   From there,  choose which Menu option you need to make changes to.   The example below uses the Quick Links Menu, although this process will work with any of the menus.     

Click Edit under the “Operations” column beside the link you want to edit or delete.  Update any menu link information on the Edit menu link screen and click “Save” or “Delete.”  Save will take you to the page of the link you edited with a confirmation.  Delete will bring you to a final “Are you sure you want to delete this link” page. Click Delete Or Cancel.