unpinning the signal light wire from headlamp 5 pin connector
 

i have an 02 c240 and my front turn signal went out. i bought an updated socket from the local mb dealership which required that i unpin the signal light wire the 5 point headlamp connector. i went as far as taking the connector lock but i cannot remove the wire itself. i don't know if there is a lock somewhere and i'm scared to yank it hard for fear that it might break.does anyone know how? or is there a website with a diagram i can follow?
p.s. the local mb dealership is charging me $150.00 for labor.