.afterregisterdetails{
    display: none;
    
}

#afterregisterloginform{
 display: none;   
}

.livestreamheader, #standsendmessagediv {
 display: none;   
}
<br />
<b>Warning</b>:  Trying to access array offset on false in <b>/var/jmdb/tvcc/delegateinstances/srms23/css/custom.php</b> on line <b>17</b><br />