The Select Assembly drop-down list shows all assemblies Blue Integrator is configured for.  Select the appropriate assembly.  The Select Transport drop-down list will then show all transports that apply to that assembly.  If there are no transports available for the selected assembly, an error dialog is displayed.

To remove a custom transport from Blue Integrator, highlight the transport in the right pane of the Custom Transport Library window under Static Configuration and then click the Delete button.  After confirmation of the action, the transport is deleted.