The following command deletes an object from a bucket named my-bucket:

aws s3api delete-objects --bucket my-bucket --delete file://delete.json

delete.json is a JSON document in the current directory that specifies the object to delete:

{
  "Objects": [
    {
      "Key": "test1.txt"
    }
  ],
  "Quiet": false
}

Output:

{
    "Deleted": [
        {
            "DeleteMarkerVersionId": "mYAT5Mc6F7aeUL8SS7FAAqUPO1koHwzU",
            "Key": "test1.txt",
            "DeleteMarker": true
        }
    ]
}