how do I delete installed github app from my github organization

I have never worked in ruby before . Github has a script that runs in ruby for JWT generation . I've been trying to run that script on repl.it and have been failing . This is a screen shot of the error i'm getting . and this is a link to github docs referring to the same script -> https://docs.github.com/en/free-pro-team@latest/developers/apps/authenticating-with-github-apps#authenticating-as-a-github-app .

I've been trying to generate this token through javascript but i get Integration not found error everytime i use that token .

const privateKey = fs.readFileSync("key.pem");
const currentDate = new Date();
const nowTime = Math.floor(currentDate.getTime() / 1000);
const payload = {
  // issued at time
  iat: nowTime,
  // JWT expiration time (10 minute maximum)
  exp: 600 + nowTime,
  // GitHub App's identifier
  iss: 12345678,
};
const token = jwt.sign(payload, privateKey, { algorithm: "RS256" });

Error i get when calling through postman

Link to github docs referring to the deletion of installed apps -> https://docs.github.com/en/free-pro-team@latest/rest/reference/apps#delete-an-installation-for-the-authenticated-app