Chairman David Keyte said: "As a club we are bitterly disappointed and deeply concerned at the results and performances so far this season and feel we have to take action."
Davey succeeded Graham Turner at Edgar Street in the summer after leaving Darlington.
The former Barnsley manager joined the Teesside club in April but could not prevent them being relegated to the Blue Square Bet Premier.
He quit that job in June by email.
His only win as Hereford boss came on the first day of the season against Crewe.
Watch highlights of Simon Davey's last game in charge of Hereford
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