Remove Characters from a String with limited Memory

How about, If we don't have enough memory we have to use a single array.
Here is how to do that with limited memory

  public static string RemoveCharactersLimited(char[] s, string removeChars)
        {
            int i = 0, j = 0;

            int lengthC = removeChars.Length;
            int lengthS = s.Length;
            int[] intCollection = new int[256];
            
            for (i = 0; i < lengthC; i++)
            {
                intCollection[removeChars[i]] = 1;
            }

            i = j = 0;
            for (i = 0; i < lengthS; i++)
            {
                if (intCollection[s[i]] != 1)
                {
                    s[j] = s[i];
                    j++;
                }
            }
            while (j < lengthS)
            {
                s[j] = '\0';
                j++;
            }

            return new string(s);

        }