You cannot delete a connection if the connection is used as part of the integration definition or if it is used in data mapping for posting. See Defining Integrations.
To delete a connection:
In your application, select Manage, and then System Settings. In System Settings, select Connection, and then select a connection.
Select Actions, and then Delete.
Click Yes to the question, “Are you sure you want to delete (connection name).”
Click Save, Save and Close, or Cancel.