Try using a pair of tweezers or small pair of pliers to remove the micro sd card. If you don't have any of those, try using a toothpick and rocking the micro sd card back and forth out of the slot. The toothpick won't scratch the various plastics of the GoPro either, so it's worth a shot.

Also, It would be wise to attempt micro sd card removal with the battery removed from the camera.

Good luck!