This operation removes a bitmapped image from the screen and frees the memory used by that bitmap. It takes only one parameter, the handle of the bitmap returned by WBITMAP-DISPLAY. This should be either USAGE COMP-4 or unsigned DISPLAY.
When an image is removed from the screen, it's replaced by spaces using the current window's background color. Only those parts of the screen that are currently showing the image are updated.
You can effectively remove an image from the screen by displaying over it. However, this does not free the memory used by the image. The runtime also spends some time whenever it updates the screen determining whether or not the image is visible. For these reasons, you should destroy images when you are done with them.
The runtime automatically destroys all remaining images when it shuts down.