Token_12.js

...
} else if(event.message.text === 'revoke') {
    let token = await admin.database().ref('token').child(event.source.userId).once('value');
    
    await initialLINE(token.val().token_type, token.val().access_token );
    await admin.database().ref('token').child(event.source.userId).remove();
    // 13. Reply result to User Chat Room
    // 14. Revoke Access Token
}
...