save_post affect creation and deletion

There are something wrong in your code, Here I edited what you tried,

function rohs_update_title($post_ID){

$post_type = get_post_type($post_ID);

// If this isn't a 'rohs_menu' post, don't update it.
if ( "rohs_menu" != $post_type ) return;

$postAuthorId = get_post_field( 'post_author', $post_ID ); // get the post author ID

$userToGetData="user_".$postAuthorId;
$restaurantName = get_field( 'nom_restaurant', $userToGetData );
$date = get_field('date');

remove_action( 'save_post', 'rohs_update_title' );

$menuName="Menu du ".$date.' chez '.$restaurantName;  
wp_update_post( array( 'ID' => $post_ID, 'post_title' => $menuName ) );

add_action( 'save_post', 'rohs_update_title' );
}
add_action( 'save_post', 'rohs_update_title', 10, 1 );

Now try this and let me know