When a member post to a group it shows up in the activity feed under “username posted an update in the group” then its followed by the group avatar then the group name. So I was wonder how I could remove the group avatar from the activity action. Is their anything I could add to the functions.php or bp-customs.php? I would rather not try hiding it through css.
Add this to your child theme's functions.php.
And it will override bp default's and only show the secondary avatar when the activity is a friends update (eg. Bob became friends with Joe.)