How to remove time in comment?

Exactly what you do depends on your theme. If it is a freely available theme, post a link to your site so we can see the code so we can help .
You can remove the date easily editing the CSS of your theme.

i dont know any filter but you can remove the date from wp-core if you dont need that and have access on ftp
what you must change is located in wp-includes/comment-template.php

at line 1986, change this <?php printf( _x( '%1$s at %2$s', '1: date, 2: time' ), get_comment_date(), get_comment_time() ); ?>

with
<?php printf( get_comment_date() ); ?>

after you will see something like this

Look out when your wordpress version will update maybe you must change again that line of code, for this reason is a bad idea to change core files

with this in function.php i think you will remove the time but will remain the word “at”;

add_filter('get_comment_time','time_remove');
function time_remove( ) {
}