delete_group(group_key, group_id, modifiers, callback) {
        const identifiers = {$group_key: group_key, $group_id: group_id};
        this._delete_profile({identifiers, modifiers, callback});
    }
groups.delete_group(group_key, group_id, modifiers, callback)
        ---
        delete a group profile permanently

        usage:

        mixpanel.groups.delete_group('company', 'Acme Inc.');