You push the latch/clip towards the motherboard. I wouldn't advise using a screwdriver, as I've done that just this week, and scratched my motherboard. Doing that can result in it breaking.
It can be a bit tricky getting your graphics cards out of your case, even when pushing the latch to release your graphics card. It helps me when pulling on the left side of the card first (where you screw it down).
Good luck!