In a message to supporters Jama said: "I would just like to thank all the players, volunteers, and fans. You have been impeccable.
"The work on the the ground improvements, night and day, to achieve Northern League status was incredible, so credit to Craggsy and everyone at the club for making it a reality. I'm their biggest fan.
"We did what nobody thought was possible and I'm incredibly proud of that."
The transformation of the first team's fortunes during Jama's five year tenure in charge of the Boysie is a testament to his hard work and dedication both on and off the pitch.
By securing second place in the North Riding Premier Division last season, our highest league finish in 13 years, and thus ensuring promotion to the Northern League for the first time in our 80+ year history, Jama leaves a solid foundation for his successor to build upon.
The club would like to place on record our thanks to Jama and wish him all the best in his feature endeavours.
An update regarding first team management arrangements will be circulated in due course.