Removes a Project instance from the list of projects in use.

        :param project_id: Project identifier

def remove_project(self, project_id):
        """
        Removes a Project instance from the list of projects in use.

        :param project_id: Project identifier
        """

        if project_id not in self._projects:
            raise aiohttp.web.HTTPNotFound(text="Project ID {} doesn't exist".format(project_id))
        del self._projects[project_id]