Need help on fast and efficient logic of destroying random balls.

Hi, I am new bee, and I want to build 2D game in Unity 3d. Game is just like when user ball hit any other ball and destroying those who are near to collider ball like I am showing in screen shot three blue ball I want to delete from array and also destroy. I know how to destroy and delete from array but getting stuck in logic building. Let say If hit most left blue ball which has 4th index in array and then I'll compare this 4th Index object with rest of array's object if it is less or equal to 0.2 then destroy and also delete, so if 4th index distance equal to 5th index and same 5th index equal to 6th index and then compare to rest of, I think it'll have to check n for n. Kindly suggest me fast and efficient logic for this. I have attached screen shot and also code which is incomplete.

           void OnCollisionEnter2D(Collision2D coll) {
            GameObject[] temp = new GameObject[10];       
     int tempCounter=0;
     for(int x =0;x<CreateDynamicsObjects.blueBallsArray.Length;x++){
         if(CreateDynamicsObjects.blueBallsArray[x].name==name){
             temp[tempCounter]=CreateDynamicsObjects.blueBallsArray[x];
             tempCounter++;
             break;
         }
     }

     int loopCounter =0;
     while(temp.Length>loopCounter){
         for(int y =0;y<CreateDynamicsObjects.blueBallsArray.Length;y++){
             float distance = Vector3.Distance(temp[loopCounter].transform.position,CreateDynamicsObjects.blueBallsArray[y].transform.position);
             if(distance<0.3){
                 for(int z=0;z<tempCounter;z++){
                     if(CreateDynamicsObjects.blueBallsArray[y].name!=temp[z].name){
                         if(temp.Length>tempCounter){
                             temp[tempCounter]=CreateDynamicsObjects.blueBallsArray[y];
                             tempCounter++;
                         }

                     }
         
                 }

             }
         }
         loopCounter++;
     }
     if(temp.Length>0){
         for(int i=0;i<temp.Length;i++){
             Destroy(temp[i]);
         }
     }  }

CreateDynamicsObjects.blueBallsArray is my array for blue ball. Thanks.