A set of essentially identical panels, such as building panels, provided with a mechanical locking system including a displaceable tongue arranged in a displacement groove having a first opening at a first edge of a first panel. The tongue is configured to be displaced in the displacement groove along a displacement axis to attain a locking state wherein a first portion of the tongue cooperates with a first tongue groove having a second opening at a second edge of an adjacent second panel, for vertical locking of the first and the second edge. A second portion of the tongue is configured to cooperate with the second edge of the adjacent second panel via an elongated element for vertical unlocking of the first and the second edge.