How to delete file opened by a Canvas

Question

hello guys, 

 

 I'm opening a .bmp image created on a folder on a InkCanvas to draw on like below. And when i'm closing it i want the TempFile to be deleted. but when i try to delete it says the file is used by another process. is there anyway to do this? I'm using WPF C#. Please help me out.

 

Thanks  you! :)

 

img = new BitmapImage(new Uri(TempFile, UriKind.Relative));

myImageBrush = new ImageBrush(img);
myCanvas = new Canvas();
myCanvas.Width = img.Width;
myCanvas.Height = img.Height;
myCanvas.Background = myImageBrush;

cw.ImgPO.Height = img.Height;
cw.ImgPO.Children.Add(myCanvas);