How to remove extra subnets from a network adapter in Threat Management Gateway (TMG)?

Question

Forefront Threat Management Gateway

A strange problem has appeared on the TMG server. When you turn on an external network adapter, routes that it does not serve are hung on it.
Example:
TMG three networks External, Internal, Site-To-Site.
External 89.234.78.159( subnet 255.255.255.0 ) gateway 89.234.78.158
Internal 10.0.0.
Site-To-Site 10.1.0.1 gateway 10.1.0.2 networks behind it 10.2.0.0 255.255.0.0
While the External adapter is disabled, the routes are normal, as soon as I turn on the route to 10.1.0.2 appears through the interface 89.234.78.159 and routes to all subnets through the gateway 10.1.0.2 from interface 89.234.78.159 which are behind this gateway( 10.1.0.2 ). Correct routes are also saved.
At the same time, in the Route Information for this interface (you can see if you add the adapter subnet to networks ), all these networks are registered.
I tried to delete these routes manually, it helps exactly until the reboot, these routes are not in the registry, I did not register them with static.
How can I untie the subnet data from the adapter?