if you're not the author you can't
but we can give access to authors to let them editing their own entry (there is a button to claim entries or an admin can give an access).
Are you interested to edit only this specific entry ? if you have actively contribute to this guide and want to update it I can give you an access.
(if you are interested to be involve on EDCodex to help us managing entries, we can give moderator access: have to be discussed in private)