I assume you are talking about an electrical connector with a wire retaining clip.
These can be frustrating little suckers.
The wire clip has to be removed before the connector can be pulled apart. I usually use a small flat bladed screwdriver to pry the clip out. Careful you don't flick the clip across the paddock when it lets go. To pry it out lever it just at the side of the center of the clip.
Hope this description helps you get the pesky clip out.
