If you no longer need a bucket, you can unbind it. This document describes how to unbind buckets that are no longer needed.
At present, you cannot delete buckets in CI Console. For information on how to delete buckets, see Deleting Buckets for COS.
After a bucket is unbound, it is removed from the bucket list in CI Console, but COS retains the bucket and all its files, which can be viewed in COS Console.