How to get AWS cognito user pool in amplify react app

I want to delete a user in Cognito user pool.
But I can’t get cognito userPoolId.

I tried as follows.
Please teach me.
const params = { Username: selectedRows[i], UserPoolId: process.env.REACT_APP_COGNITO_USER_POOL_ID };

    const result = await new Promise((resolve, reject) => {

      cognito.adminDeleteUser(params, (err, data) => {

        console.log(err)

        if (err) {

          reject(err);

          return;

        }

        resolve(data);

      });

    });

Thanks in advance.