Telligent Community enables hiding a member's forum posts from the community as a way to address aggressive members. The member will be able to see the posts that they author, but no one else will. To enable this setting, navigate to Administration > Membership > Members, search for the member, select the member, click Edit, and check the Hide this member's content from other members checkbox. Click Save.
Note that this setting only applies to forum content at this time. You may also consider flagging the member as abusive and having them work through the abuse workflow, as well.