How do you fire your therapist?

I haven't "fired" my therapists but I have said I felt like I didn't need treatment any more. Unless you are under a Court order, you can't be forced into it. It's your call when you want to end treatment. You could even use your second example as a reason because that's perfectly valid. I do recommend ending on a good note so that in case you need help down the road you feel comfortable calling that therapist again. I had to do that because I needed a recommendation for my sister.