Most connectors have built-in clips on the side(s). I often use a small screwdriver to help me pry the clip away from the connector a little bit so as to unhook it and allow for the connector ends to pull apart.
Some other connectors, however, require pressing in a little "latch" that is also a part of the connector itself, before it will slide part.
Some other connectors, however, require pressing in a little "latch" that is also a part of the connector itself, before it will slide part.