Hair particles doesn't seem to disappear when i cut them?!

So I’ve been working on this for a while and I don’t know what to do… I’ve searched the web but unfortunately I didn’t find answers. Here’s what I’ve been experiencing… in the first image i’ve shaped out how i want my brows to look like but instead i get this(2nd image)

a more obvious example… i’ve cut a straight line through the hair particles and this is what i get…

So is there a way to cut hair without leaving any trace behind?
by the way i use blender 2.8 the stable release