Symptoms:
This issue occurs when attempting to delete Service insertion entities which still have dependencies.
This issue is resolved in VMware NSX-T Data Center 3.2.1
Workaround:
Please review the configuration in the UI, System > Service Deployments > Deployments and System > Service Deployments > Service Instances and remove any dependencies, then attempt to remove the service attachment.
If this is still failing, please open a support request with Broadcom Support and refer to this KB article.