Actually, you can delete by right-clicking <_< and this is a WIP project, so giving a positive comment is better :P
I have some problems with right clicking. When you move your mouses fast it may create several circle holes. I don't know why.
Maybe it's because the game doesn't update fast enough :\
No, it's because the mouse does not move pixel by pixel. It can move 20 pixels instantly. The way to solve the problem is to connect a line between the last mouse point and the current. However I have some problems with the right mouse (this method doesn't work???)