To delete a case, simply open a case and click on "..." then select Delete Case.
Another way is to navigate to the bottom of the case screen and select the "Delete" button.
💡Note: Deleting a case deletes that case and all associated child records such as comments, documents, communications, passports, family data etc.
Employee records (that may be used by other cases) are not deleted - delete the employee if this is what you want.