The Crowd Control badge is for "Helping teammates by kicking 50 enemies"
You get this by interacting with an enemy who has grabbed a co-op partner. You can get this in all trials but the first "Kill the snitch" is a good one to do this in as there are multiple enemies you can farm this on pretty early.
Also two handy things to note:
1. The in-game badge menu tracks your progress.
2. Leaving a trial after gaining progress still counts towards it.
Video guide for reference: