IBM Cloud - The computer says "No"

Whilst trying to delete an IBM Cloud Object Storage (COS) instance from the command-line: -

ic resource service-instance-delete e8c79678-2ef8-4c7c-8a89-24ff2e85e691 --force

I saw: -

Deleting service instance e8c79678-2ef8-4c7c-8a89-24ff2e85e691 in resource group default under account DAVID HAY's Account as david_hay@uk.ibm.com...
FAILED
Cannot delete instance or alias, resource keys must first be deleted.

and couldn't quite work out to what it was referring.

Thankfully, the help text for that command had the answer: -

ic resource service-instance-delete --help

FAILED
Incorrect Usage.

NAME:
  service-instance-delete - Delete service instance

USAGE:
  /usr/local/bin/ibmcloud resource service-instance-delete ( NAME | ID ) [-g RESOURCE_GROUP] [-f, --force] [--recursive] [-q, --quiet]
  
OPTIONS:
  -g value     Resource group name
  -f, --force  Force deletion without confirmation
  --recursive  Delete all belonging resources
  -q, --quiet  Suppress verbose output

ic resource service-instance-delete e8c79678-2ef8-4c7c-8a89-24ff2e85e691 --force --recursive

Deleting service instance e8c79678-2ef8-4c7c-8a89-24ff2e85e691 in resource group default under account DAVID HAY's Account as david_hay@uk.ibm.com...
OK
Service instance cos_for_roks with ID crn:v1:bluemix:public:cloud-object-storage:global:a/f5e2ac71094077500e0d4b1ef85fdaec:e8c79678-2ef8-4c7c-8a89-24ff2e85e691:: is deleted successfully