technical question about s3 bucket policies

Hello.

In that case, you will need to access it as the root user of your AWS account and delete the S3 bucket policy.
https://repost.aws/knowledge-center/s3-accidentally-denied-access

You can access AWS as the root user by following the steps in the document below.
However, the root user is the user who can perform all operations, so please be careful when operating.
https://docs.aws.amazon.com/signin/latest/userguide/introduction-to-root-user-sign-in-tutorial.html