Solved, found this code snipped from a previous post https://bbpress.org/forums/topic/prevent-users-from-creating-topics-2/ which removed the topic form for everyone but admins and moderators.
add_filter( 'bbp_current_user_can_access_create_topic_form' , 'rew_only_mods' , 10 , 1) ;
function rew_only_mods ($retval) {
// Users need to earn access
$retval = false;
//check if admin
if ( bbp_is_user_keymaster() ) {
$retval = true;
}
//check if moderator
$role = bbp_get_user_role( get_current_user_id());
if ($role == 'bbp_moderator') {
$retval = true;
}
// Allow access to be filtered
return (bool) apply_filters( 'rew_current_user_can_access_create_topic_form', (bool) $retval );
}