To remove your AirPods Case, you need to press the bottom of the case, where you insert your charger.
To remove a case that is stuck, we recommend using a small object to push your AirPods out of the case (though not a too small object, we do not want it to cause any damage to the charging input). One suggestion is to use your charger to push your AiPods out.
NOTE! Never use objects that could damage your AirPods.