add_action('wcfmmp_store_follow_me', function() {
    global $WCFMu;
    // removes WCFM function completely
    remove_action('wcfmmp_store_follow_me', [ $WCFMu->wcfmu_vendor_followers, 'wcfmmp_store_follow_me' ], 16);

    // Write you own logic here
    // You can copy-paste the old function content here then edit as you need

}, 15);