Follow these steps.

1. Talk to the person who is abusing.
2. If he/she doesn't listen to you, warn him/her.
3. Take screenshots of the so-called abuse as indisputable proof in case he/she abuses again.
4. Warn him/her again and tell him/her that the next time he/she will be kicked if he/she continues. If possible, report the abuse at that time so you won't forget important details.
5. Kick him/her. Yeah, it doesn't matter if it's another ACR member. He/She will (hopefully) learn something.
6. Come to the forums, upload the snap and explain both the committed abuse and the kick.

Hopefully Bug will do something about it.
No one is allowed to ban the abuser. However, if someone does, follow steps 3 (quickly), 5 and 6.
The only one authorized to ban and setlevel is Bug unless he allows other people to.