Self employment income defaults to commission based and I cannot change this. Why? I am professional services, not commissioned

Did you receive a T-slip with commission on it? If so, you won't be able to change what type of business it is. 

There was no T-slip.

It was one payment as an independent contractor. 

If there's no T-slip, then you can remove the existing self-employment profile, and then recreate it as a Professional one. There’s no way to change the type of an existing profile.