Mantack joined the Gladiators back in August and went on to feature 13 times for the club in all competitions.
The 24-year-old has featured for a range of clubs throughout his career, having first progressed through the youth ranks at Oldham Athletic.
He made his only League One appearance for the club in August 2017.
Loan spells at Alfreton Town, FC United of Manchester and Stockport County followed for Mantack, who has also been with Altrincham, Ashton United, Curzon Ashton and Stalybridge.
Discussing the departure, Matlock chairman Jay Beaumont said: "We would have liked to see Kallum remain at the club and made him what we consider a good offer, however he told us of his desire to play closer to home due to personal reasons.
“As a club and community, we understand and respect that. He leaves with nothing but our best wishes."
Keep up-to-date with our exclusive email newsletters.
Subscribe