如何删除动态生成的控件

        PictureBox pic;
        Label label1, label2;            // 初始化怪物的控件
            foreach (string key in gm.Game.CurrentLevel.Monsters.Keys)
            {
                UIContainer monsterContainer = new UIContainer();                 pic = new PictureBox();
                //背景色为透明
                pic.BackColor = Color.Transparent;
                pic.SizeMode = PictureBoxSizeMode.AutoSize;
                //初始位置是怪物对象的初始位置
                pic.Location = gm.Game.CurrentLevel.Monsters[key].OriginalLocation;
                //怪物图片
                pic.Image = gm.Game.CurrentLevel.Monsters[key].Image;
                //右键指定
                pic.ContextMenuStrip = this.cmsAttack;
                //保存怪物key
                pic.Tag = key;
                //描绘到窗体
                this.Controls.Add(pic);
                //保存一个容器对象
                monsterContainer.Pic = pic;
                
                 label1 = new Label();
                //显示原始生命值长度
                label1.Size = new Size(gm.Game.CurrentLevel.Monsters[key].OriginalBlood, 20);
                label1.AutoSize = false;
                label1.BackColor = Color.Red;
                label1.BorderStyle = BorderStyle.FixedSingle;
                //位置在PictureBox上方
                label1.Location = new Point(
                    gm.Game.CurrentLevel.Monsters[key].OriginalLocation.X,
                    gm.Game.CurrentLevel.Monsters[key].OriginalLocation.Y - 25
                    );
                this.Controls.Add(label1);
                monsterContainer.LabelBlood = label1;
                                 label2 = new Label();
                //显示当前生命值
                label2.Size = new Size(gm.Game.CurrentLevel.Monsters[key].CurrentBlood, 20);
                label2.AutoSize = false;
                label2.BackColor = Color.Yellow;
                label2.BorderStyle = BorderStyle.FixedSingle;
                label2.Location = new Point(
                    gm.Game.CurrentLevel.Monsters[key].OriginalLocation.X,
                    gm.Game.CurrentLevel.Monsters[key].OriginalLocation.Y - 25);
                this.Controls.Add(label2);
                monsterContainer.LabelHurt = label2;
                //放在最顶层
                label2.BringToFront();                UIMappings.Add(key, monsterContainer);
            }