how can i take out the version in my main.css file? [duplicate]

Question

You can remove query strings from scripts and style sheets with a function in the theme’s functions.php file.

// Remove Query Strings from enqueue scripts
add_filter( 'style_loader_src', 'remove_query_string' ); // CSS files
add_filter( 'script_loader_src', 'remove_query_string' ); // javascripts
function remove_query_string( $url )
{
    return remove_query_arg( 'ver', $url );
}

Be sure you have made a child theme so you don’t lose changes upon a theme update. See Child Themes « WordPress Codex