Remove knob from middle hole area

I have a weird question - when milling on our 3 axis cnc, and making an hole inside the part, lets say a triangle hole in the middle on the sheet, it does all the miling just fine but leabes a little knob on the part that will be thrown out - the traingolar part that was removed... i know it doesn't change the real parts function or anything like that but I just want a perfect traingle from the extra material the goes to waste..

We are using fusion360 as our CAM software and yes the knob shows up in the simulate option in fusion