Seemingly, if your bucket is created using Elastic Beanstalk then it will be created with a deletion policy to prevent the user from accidentally deleting the bucket. So, in order the fix this issue, you will have to edit the bucket policy and then you should be able to delete the bucket using AWS S3 console.
As for deleting the bucket using AWS CLI, apart from the commands that you have already used, there's one more that you can try:
aws s3 rb s3://bucketname --force --debug
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