How do I disable a Netmetal5 Antenna

After hours of repeated RouterOS installs, I finally got a new Netmetal 5 running as an external WiFi antenna to replace my dead Metal AC52.

I had to downgrade the OS to 6.49.22 to get the configuration to stick.

I have a Mikrotik HGO-antenna-OUT on antenna's 1 and 3. Antenna 2 has a 1-5 Mhz terminator on it.

I want to turn off antenna 2 and set the gain for the 2 remaining antenna's.

I'd appreciate some pointers on where in webfig I go to turn antenna 2 off and set the proper gain on the others.

Cheers,

Sam