WordPress media library upload restriction, just copy the code below to your functions.php
Or install this plugin to do the task WDES User Upload Restriction – https://wordpress.org/plugins/wdes-user-upload-restriction/.
add_action('pre_get_posts','wdes_users_own_attachments');
function wdes_users_own_attachments( $wp_query_obj ) {
global $current_user, $pagenow;
if( !is_a( $current_user, 'WP_User') ){
return;
}
if( !in_array( $pagenow, array( 'upload.php', 'admin-ajax.php' ) ) ){
return;
}
if( !current_user_can('delete_pages') ){
$wp_query_obj->set('author', $current_user->ID );
}
return;
}