using System;
using System.Linq;

public class Test
{
	public static void Main()
	{
        var sampleStr = "at Metadata at quota at what at batter";
        var result = string.Join(" " , sampleStr.Split().Where(w => !StringComparer.OrdinalIgnoreCase.Equals(w, "at")).ToArray());

        Console.WriteLine(result);
	}
}