Delete all images added to canvas

Do you mean you just want to remove all the child elements?

canvas.Children.Clear();

looks like it should do the job.

EDIT: If you only want to remove the Image elements, you can use:

var images = canvas.Children.OfType<Image>().ToList();
foreach (var image in images)
{
    canvas.Children.Remove(image);
}

This assumes all the images are direct child elements though - if you want to remove Image elements under other elements, it becomes trickier.