How to deal with Trolls on Facebook | Facebook
First of all any racist, sexist, bullying, or harassing people must be reported. You can do this by clicking on the “flag” link at the bottom of their post on the group page. The message will appear that you have flagged this person and that you can also report them. Click on “report” and from the dropdown menu select “attacks individual or group”. This will notify Facebook that this person is acting outside of Facebook rules, which expressly state:
1. You will not bully, intimidate, or harass any user.
2. You will not post content that: is hateful, threatening, or pornographic; incites violence; or contains nudity or graphic or gratuitous violence.
3. You will not use Facebook to do anything unlawful, misleading, malicious, or discriminatory.
Facebook themselves suggest how best to deal with trolls


