Delete BotAlias created in Amazon Lex.

I have created a chat bot using lex service and integrated it to Facebook. Now when I was doing the cleaning up part while deleting the bot created in the lex is prompting as **" this bot is currently used by an alias named RestaurantBot . Delete botAlias RestaurantBot from Restaurant. " ** As a preliminary customer of AWS I am unable to delete the application I created. Kindly request the AWS support team to resolve this problem.