Photo is very unhelpful. You'll have to inspect it closely, there might be a tab you either press or prise outwards. Sometimes they just have detents on the inside and all you can do is pull. Sometimes you can get a small screwdriver between the parts of the connector and lever it out. Sometimes a connector is actually a moulded header which is soldered in to the board, so you can't pull it off without de-soldering (though I don't think those are used much now). Often these things are counter-intuitive.
Take photo from other side!