After guiding the club to safety last season, The Lions have registered just one win from their first seven games, writes Tom Feaheny.
Lockwood becomes the sixth manager across the three National League divisions to depart.
A club statement read: "Guiseley AFC have today taken the decision to part company with Adam Lockwood and his assistant, Dave Penney, with immediate effect.
"The club wishes to place on record its thanks to Adam and Dave, in particular for their efforts in keeping the club in the National League last season. Guiseley AFC will be making no further comment at this stage."