How to Hide StifLi Backup Tools Admin Menus

function plt_hide_stifli_backup_tools_menus() {
	//Hide "StifLi Backup".
	remove_menu_page('stifli-backup-tools');
	//Hide "StifLi Backup → Backups".
	remove_submenu_page('stifli-backup-tools', 'stifli-backup-tools');
	//Hide "StifLi Backup → Migration".
	remove_submenu_page('stifli-backup-tools', 'stifbt-migration');
	//Hide "StifLi Backup → Staging".
	remove_submenu_page('stifli-backup-tools', 'stifbt-staging');
	//Hide "StifLi Backup → Scheduled Backups".
	remove_submenu_page('stifli-backup-tools', 'stifbt-scheduled');
	//Hide "StifLi Backup → Settings".
	remove_submenu_page('stifli-backup-tools', 'stifbt-settings');
}

add_action('admin_menu', 'plt_hide_stifli_backup_tools_menus', 11);

Where do I put this code?