How to make a unit uncontrolable?

[X-maul]

I'm creating a map with a a "send-units-to-get-income" feature, and I want the units send to be owned by the player sending them (so the owner gets credits for the kills and stuff, the units do).
I've seen this done in a map named "Nexus Wars" (the SC2 version of the "Castle Fight" from Wc3), where it gives you an error message whenever you try to give the unit an order.

How is this done?

 

[Rainther]

A simple trigger does this. Just open Action pop up and search for "uncom" and I'm sure you'll find it.

 

[X-maul]

Thank you