如何在一个多边形被绘制后在Netbeans中清除一个JFrame ?

I made this program that draws a polygon in a JFrame and then fills it. I have recently changed it so that I have buttons that control movement of the polygon. The movement works besides one issue: when I press a button to move the polygon a direction, a new polygon is created in the new spot but the original still stays visible.I made this program that draws a polygon in a J