performance – duplicate element removal

I have tried to remove the duplicate elements from the array using c language, here I am using 3 for loops to remove the duplicate elements.

How can this optimize the code?

Are there any other simple methods to remove the duplicate elements?

#include <stdio.h>

#define MAX_SIZE 100 // Maximum size of the array

int main()
{

 int arr(MAX_SIZE); 
 int size;        
 int i, j, k;     


printf("Enter size of the array : ");
scanf("%d", &size);


printf("Enter elements in array : ");
for(i=0; i<size; i++)
{
    scanf("%d", &arr(i));
}



for(i=0; i<size; i++)
{
    for(j=i+1; j<size; j++)
    {

        if(arr(i) == arr(j))
        {
         
            for(k=j; k<size; k++)
            {
                arr(k) = arr(k + 1);
            }

     
            size--;

            j--;
        }
    }
}

printf("nArray elements after deleting duplicates : ");
for(i=0; i<size; i++)
{
    printf("%dt", arr(i));
}

return 0;
 }