The former Norwich City striker signed for the club last season and was also a coach under Ady Pennock and Jamie Day.
The club changed direction in the summer with Chesterfield’s Ian Evatt taking over.
But the National League side say Holt’s second spell at Holker Street has come to an end.
A club statement read: “Though Grant’s commitment to the club has always been strong, it was felt by both parties that the pressures of travel and the new strategic direction of the club meant that the time had come for Grant to seek a new challenge.
“The club would like to thank Grant for his time back at the club, both for his professional attitude and his high standards on and off the pitch.
“What we have learned from his experiences at the highest levels of the football pyramid will help the club move on to even greater heights.
“We wish Grant the best of luck in the next stages of his career and look forward to welcoming him back very soon.”