How to close positions or orders?

Like when after sell order is triggered I like to close Buy order if any order has been executed and when buy order is triggered, I like to close Sell order if any order has been present.

Can’t understand where to put close trade code and also how to use closetrade code in mql5. I don’t want any stop-loss and take profit methods and tickets all that. I want simple direct method.

...
#include <Trade/Trade.mqh>

input double Lots=0.01;

input ENUM_TIMEFRAMES Timeframe = PERIOD_CURRENT;

input double Step = 0.04;

input double Maximum = 0.2;

int parabolicSarHandle;


int barsTotal;


CTrade trade;

int OnInit()

 {
  parabolicSarHandle = iSAR (_Symbol,Timeframe,Step,Maximum);


  barsTotal = iBars(_Symbol,Timeframe);

 
   return(INIT_SUCCEEDED);

  }

void OnDeinit(const int reason)
  
{
   
  }

void OnTick()

    {

   double val [];


   CopyBuffer (parabolicSarHandle,0,0,2,val);

   
   int bars = iBars(_Symbol,Timeframe);


   if (barsTotal != bars)
{
      
      double close0 = iClose(_Symbol,Timeframe,0);


      double close1 = iClose(_Symbol,Timeframe,1);

   
   if  (close0 >val [1] && close1 <val [0])
 {
      
      Print (__FUNCTION__ ">Buy Signal");

      trade.Buy(Lots,_Symbol,0,0,0,"SAR BUY");

      barsTotal = bars;

    } 

   else if (close0 < val [1] && close1 > val [0])

    
{
      
      
      Print (__FUNCTION__ ">Sell Signal");

      trade.Sell(Lots,_Symbol,0,0,0,"SAR SELL");

      barsTotal = bars;

    }

   
   Comment  ("\nParabolic SAR[0]: ",DoubleToString(val[0],_Digits),


              "\nParabolic SAR[1]: ",DoubleToString(val[1],_Digits));

    }

 }

After trade.Buy execution, I want to close Sell order of the same and when trade.Sell is executed, I want to close Buy order automatically.

How do i do it?

Like trade.CloseOrder(trade.Buy) or trade.ClosePosition(trade.Sell) ?

When and where and what to write?