61 13 ... Circular Plugs, 13-Pin, System D2.5
Pull off rubber grommet (1).
Carefully pull out lock (2) in direction of arrow.
Move connector lower section (3) in direction of arrow enough for retaining lugs (4) to lock into locking groove (5).
Using special tool 61 1 132 (ejector), press down retaining hooks (6) on appropriate contact and pull out cable.