Deleting Elements from an Array based on their Position every 3 Elements

I created an array called elements_n which has the elements 0 to N-1 where N is 2. The below numbers are the elements of the array called elements_n:

0 1 

I have another array called Arr which has the following elements:

0 1 3 1 2 4 

If any of the first 3 elements of the array Arr are equal to the first element of elements_n which is 0, I would like to delete that element from the array called Arr. I then repeat the same process for the next 3 elements of the Array Arr. So to explain myself better, I will use the following example:

Compare the first 3 elements of array Arr which are 0, 1, 3 to the first element of elements_n which is 0. Since Arr[0] == elements_n[0]. I delete Arr[0] from the array Arr.

Compare the next 3 elements of array Arr which are 1, 2, 4 to the second element of elements_n which is 1. Since Arr[3] == elements_n[1]. I delete Arr[3] from the array Arr. So the elements that should be left in the array Arr are:

1 3 2 4

When I implemented it myself in C programming with the code found below the end result is coming:

 1       3       3       2       2       4

Rather than:

  1       3       2       4

This is the code I implemented:

  #include <stdio.h>
  #include <stdlib.h>
  #define N 2 

  int main()
  { 

       unsigned *elements_n = malloc(N * sizeof(unsigned));

       for (int i = 0; i < N; i++)
       {
             elements_n[i] = i; //Created an array which has the elements 0 to N-1
       }
       printf("\n");

       unsigned Arr[6] = { 0, 1, 3, 1, 2, 4 };
       unsigned position_indices[2] = { 3, 3 };  //Moving every 3 elements in the Arr array. 

       int count = 0; 
       int index = 0;
       unsigned *ptr_Arr = &Arr[0];


       do 
       {

           for (int i = 0; i < position_indices[count]; i++)
           {
               if (ptr_Arr[i] == elements_n[count])
               {
                     index = i+1; //Index of the Arr element that has the same value as the element in the array elements_n 

                     for (int j = index - 1; j < position_indices[count]-1; j++)
                     {
                          ptr_Arr[j] = ptr_Arr[j + 1];
                     }
                }

           }
           printf("\n");
           ptr_Arr += position_indices[count]-1; 
           count++;


       } while (count < 2);

       for (int i = 0; i < 6; i++)
       {
            printf("%d\t", Arr[i]);
       }
       printf("\n");

       free(elements_n);

       return 0;

  }