I don't want to your help.
What is your reason for not wanting any of my help?
I just think you are going to waste my time to be honest.
I'm sorry, I'm not trying to waste anyone's time. I just genuinely want to help you out in any way that I can.
Well I don't need it
I just usually find it wise to take help whenever offered from someone. If you do not think that they will do a good job than it makes sense to turn it down though!