"The decision has been taken with a view to preparing for the 2013/14 season and Neil Redfearn will be asked to take control of first team coaching until a permanent appointment is made," the club's statement read.
"This may well be after the end of the season dependent on the availability of the club's preferred choice to become the next manager.
"A short-list has already been prepared as Neil was always going to leave at the end of the season in the event that we did not get promotion.
"However, with availability of suitable candidates changing all the time then we will adopt a flexible approach, so as to ensure that we make the right appointment."
Warnock replaced Simon Grayson in February 2012 but will now step aside for caretaker Neil Redfearn to take the reins for the rest of the campaign.