Where to close SQLiteOpenHelper if I use singleelton one

I have the following class that allows the user to get an object SQLiteOpenHelper

import android.content.Context;

public class DBUtils {  

    private DBUtils(){

    }


    private static DBHelper dbHelper ;


    public static synchronized DBHelper getDBHelper(Context context){

        if(dbHelper == null){
            dbHelper = new DBHelper(context, ApplicationMetaData.DATABASE_NAME, null, ApplicationMetaData.DATABASE_VERSION);
        }
        return dbHelper;


    }



    public static synchronized void closeDBHelper(){

        if(dbHelper!=null )
            dbHelper.close();
        dbHelper = null;
    }


    @Override
    protected Object clone() throws CloneNotSupportedException {
        // TODO Auto-generated method stub
        throw new CloneNotSupportedException();
    }

}

I want to know where I should closepass this singleton object, I can not pass by the method onTerminate(), since it will not be called. I want to close it when the user exits my application? any solution for this