Go to the Enterprise
Gateways form. 
Select the EX Controller you want to delete and click Delete.
Click OK to confirm deletion.
You can remove an EX Controller from the MiVoice Business network using the Delete operation. Before deleting an EX Controller from the MiVoice Business network, all mappings between the selected EX Controller and SIP trunks must be removed. The system scans the gateway trunk profiles for any references to the selected EX controller. If any reference is found, the Delete operation fails and an error message is displayed.
NOTE: The trunk profiles referencing the EX Controller must be manually deleted in the Gateway Trunk Profiles form before deleting the EX Controller.
To delete an existing EX Controller:
Go to the Enterprise
Gateways form.
Select the EX Controller you want to delete and click Delete.
Click OK to confirm deletion.