The API that the Spaces dashboard calls is an internal implementation detail. It's how our Ember front end talks to our backend. Under the hood, it is still accessing the same S3-compatible API from the linked docs.

A "folder" is actually just a "key" with a zero sized "object." Items inside the folder have the folder key as a prefix to their own key. For example, here is a listing of objects in a Space with a folder named foo containing a file named bar:

$ aws s3api --endpoint-url https://nyc3.digitaloceanspaces.com --profile do list-objects --bucket my-bucket
{
    "Contents": [
        {
            "LastModified": "2017-10-17T17:50:50.840Z", 
            "ETag": "\"d41d8cd98f00b204e9800998ecf8427e\"", 
            "StorageClass": "STANDARD", 
            "Key": "foo/", 
            "Owner": {
                "DisplayName": "681451698", 
                "ID": "681451698"
            }, 
            "Size": 0
        }, 
        {
            "LastModified": "2017-10-17T17:56:08.583Z", 
            "ETag": "\"8cf8463b34caa8ac871a52d5dd7ad1ef\"", 
            "StorageClass": "STANDARD", 
            "Key": "foo/bar", 
            "Owner": {
                "DisplayName": "681451698", 
                "ID": "681451698"
            }, 
            "Size": 2
        }
    ]
}

The API does not support recursively deleting files per se. On the backend, we list all objects with that prefix and then delete them. You can achieve this same result by including a prefix query parameter when calling the API to list the contents of a Space. Here's a quick Python example:

import boto3

session = boto3.session.Session()
client = session.client('s3',
                        region_name='nyc3',
                        endpoint_url='https://nyc3.digitaloceanspaces.com',
                        aws_access_key_id='ACCESSKEY',
                        aws_secret_access_key='SECRETKEY')


resp = client.list_objects(Bucket='my-bucket', Prefix='foo/')
objects_to_delete = []
for obj in resp['Contents']:
     objects_to_delete.append({'Key': obj['Key']})

response = client.delete_objects(Bucket='my-bucket',
                                 Delete={
                                     'Objects': objects_to_delete
                                 })

print("Deleted: {0}".format(response['Deleted']))

Hope that helps!