We've implemented a new feature that will allow you to retreat squads off the map and put them back in your company pool. It's shown where the normal squad upgrades are shown. It works like a toggle. If you have it on and the company is either ordered to or retreats to the offmap position, they will despawn. This doesn't kill them however, only sends them back to your company pool. They will be unavailable for the rest of that battle but will retain their experience and be available for future battles.
Example:
Here's an brief example of a platoon display. The hover is over the first icon above the command bar, normally the HQ icon. As you can see I have two platoons in this group. I've called in one; it happens to be the airborne squad dropping.
That's another feature of the platoon system, if you have airborne units, they have to be grouped into platoons together without ground forces. They drop all at once simulating an actual plane flying over. They are not reinforcable.