How to get the bot to close my manual trades?

Please help this is the code.
using System;
using System.Linq;
using cAlgo.API;
using cAlgo.API.Indicators;
using cAlgo.API.Internals;
using cAlgo.Indicators;

namespace cAlgo.Robots
{
    [Robot(TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
    public class Strat3 : Robot
    {
        [Parameter("Evaluation Time ", DefaultValue = 3600)]
        public int EvaluationTime { get; set; }

        [Parameter("Volume ", DefaultValue = 100, MinValue = 10, Step = 10)]
        public double Volume { get; set; }

        [Parameter()]
        public DataSeries MaPrice { get; set; }

        [Parameter("MaType", DefaultValue = MovingAverageType.Weighted)]
        public MovingAverageType MaType { get; set; }

        [Parameter("DPO Period", DefaultValue = 3)]
        public int DPOPeriod { get; set; }

        [Parameter("RVI Period", DefaultValue = 9)]
        public int RVIPeriod { get; set; }

        private Position OpenPosition;
        private int pips = 2;

        private double _Tenkan;
        private double _DPrice;
        private double _RVi;
        private double _Signal;
        private double _CurrentPrice;

        private RelativeVigorIndex _RVI;
        private IchimokuKinkoHyo _Ichi;
        private DetrendedPriceOscillator _DPO;

        protected override void OnStart()
        {
            Timer.Start(EvaluationTime);
            _RVI = Indicators.GetIndicator<RelativeVigorIndex>(RVIPeriod, MaType);
            _DPO = Indicators.DetrendedPriceOscillator(MaPrice, DPOPeriod, MaType);
            _Ichi = Indicators.IchimokuKinkoHyo(5, 9, 26);
        }

        protected override void OnTimer()
        {
            _Tenkan = _Ichi.TenkanSen.LastValue;
            _DPrice = _DPO.Result.LastValue;
            _RVi = _RVI.Result.LastValue;
            _Signal = _RVI.Signal.LastValue;
            _CurrentPrice = MarketSeries.Close.LastValue;

            if (OpenPosition == null)
            {
                if (_RVi > _Signal && _DPrice > 0 && _CurrentPrice < _Tenkan)
                {
                    VolumeReset();
                    var Result = ExecuteMarketOrder(TradeType.Buy, Symbol, Volume);
                    OpenPosition = Result.Position;
                }

                else if (_Signal > _RVi && _DPrice < 0 && _CurrentPrice > _Tenkan)
                {
                    VolumeReset();
                    var Result = ExecuteMarketOrder(TradeType.Sell, Symbol, Volume);
                    OpenPosition = Result.Position;
                }
            }

            if (OpenPosition != null)
            {
                foreach (var position in Positions)
                    if (position.TradeType == TradeType.Buy)
                        if (_RVi < _Signal && _DPrice < 0)
                        {
                            CloseOpenPosition();
                        }

                foreach (var position in Positions)
                    if (position.TradeType == TradeType.Sell)
                        if (_RVi > _Signal && _DPrice > 0)
                        {
                            CloseOpenPosition();
                        }
            }
        }

        private void CloseOpenPosition()
        {
            ClosePosition(OpenPosition);
            OpenPosition = null;

        }
        private void VolumeReset()
        {
            Volume = (Account.Balance / 0.7) / 5;
            Volume = Symbol.NormalizeVolumeInUnits(Volume, RoundingMode.Down);
        }

    }
}

Hi,

To close a position you just have to pass the position to ClosePosition method and it will close it.

Please check the references for example code: 

Method ClosePosition | API reference | cTrader Community

cAlgo API Reference - Positions Interface (ctrader.com)

cAlgo API Reference - Position Interface (ctrader.com)