Robson shared the role with former Ajax and Juventus midfielder Edgar Davids who signed as a player/coach in October this year.
The 43-year-old leaves the club with immediate effect while Davids will continue in his role as head coach and takes full responsibility for first-team matters.
The Bees have recently won back-to-back games, including victory over league leaders Gillingham, to lift them out of the relegation zone.
A club statement read: "Barnet FC can today confirm that Mark Robson has left his duties as joint head coach at the club.
"It was felt that clarification was required regarding the coaching responsibilities at the club and to this end it was agreed that Mark should leave with immediate effect.
"The club would like to thank Mark for all his efforts and hard work and wish him the very best for the future."
- Sports & Recreation
- Edgar Davids