[FG28_Kodiak]

I use this to remove statics:

using System;
using System.Collections;
using System.Collections.Generic;
using maddox.GP;
using maddox.game;
using maddox.game.world;


public class Mission : AMission
{

    private static string userdocpath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
    private static string FILE_PATH = userdocpath + @"\1C SoftClub\il-2 sturmovik cliffs of dover\missions\Test\";
    private static string MISSION = FILE_PATH + "StaticTestSub.mis";

    Dictionary<GroundStationary, int> StationaryMisRelation = new Dictionary<GroundStationary, int>();



    public override void OnBattleStarted()
    {
        base.OnBattleStarted();

        MissionNumberListener = -1;
    }


    public override void OnMissionLoaded(int missionNumber)
    {
        base.OnMissionLoaded(missionNumber);

        GamePlay.gpLogServer(null, "OnMissionLoaded: {0}", new object[] { missionNumber });

        foreach (GroundStationary gs  in GamePlay.gpGroundStationarys())
        {
            if (!StationaryMisRelation.ContainsKey(gs))
                StationaryMisRelation[gs] = missionNumber;
        }
    }


    private void RemoveStationary(int missionNumber)
    {
        List<GroundStationary> KeysToRemove = new List<GroundStationary>();

        foreach (KeyValuePair<GroundStationary, int> kvp in StationaryMisRelation)
        {
            if (kvp.Value == missionNumber)
            {
                kvp.Key.Destroy();
                KeysToRemove.Add(kvp.Key);
            }
        }


        foreach (GroundStationary groundStationary in KeysToRemove)
        {
            StationaryMisRelation.Remove(groundStationary);
        }
        
    }

    public override void OnTrigger(int missionNumber, string shortName, bool active)
    {
        base.OnTrigger(missionNumber, shortName, active);

        if (shortName.Equals("MisLoad"))
        {
            GamePlay.gpLogServer(null, "MisLoad: {0}", new object[] { MISSION });
            GamePlay.gpPostMissionLoad(MISSION);
        }


        if (shortName.Equals("Trigger"))
        {
            
            foreach (KeyValuePair<GroundStationary, int> kvp in StationaryMisRelation)
            {
                GamePlay.gpLogServer(null, "Stationary: {0}; MissNr.: {1}", new object[] {kvp.Key.Title, kvp.Value});
            }
        }


        if (shortName.Equals("DeleteTrigger")) // from submission
        {
            GamePlay.gpLogServer(null, "DeleteTrigger MissionNr.: {0}", new object[] { missionNumber });

            RemoveStationary(missionNumber);
        }
    }

}

Explanation:
I store the GroundStationary with the missionNumber in a Dictionary. If a new (sub)mission is loaded i check in OnMissionLoaded if there are new Stationaries created if so i store them in the dictionary with their missionNumber.
If the submission triggers (in this example) the "DeleteTrigger" i remove all statics with this missionNumber.