You should establish Guidelines for the group and then enforce them.? The owner is providing a forum and sets the rules for participation in that forum.? Members that do not play by the rules can be banned.? my 2? worth...
See?
/g/GroupManagersForum/guidelinesAlso see the groups.io terms of service which state, among other things, "... You agree to not use the Service to?email or otherwise upload any content that?is unlawful, harmful, threatening, abusive, harassing, tortious, excessively violent, defamatory, vulgar, obscene, pornographic, libelous, invasive of another¡¯s privacy, hateful racially, ethnically or otherwise objectionable...."
Toby