These days, you can only log in using 3rd party sites (such as facebook). To detach those, see below. Otherwise, if you have an ‘old’ account at eHow itself, you may try the deletion link.
URLS:
http://www.ehow.com/
http://www.ehow.com/users/delete/
Please note that AccountKiller.com is not associated with the business listed on this page. AccountKiller provides easy-to-understand instructions and guides on how to cancel charges and relationships from the list of businesses on our site, we have no affiliation with these businesses.