I have never told any family member that I want them out of my life and meant it. May have done it the 'teenage angst' years, but those are generally brushed aside.
Do I wish I had the courage to say it to a family member now? Hell yes! One in particular is making my life very difficult and creating an unhappy place to be. It's all excused with "We're too different, we could never get on." and phrase like that. Yesterday I found that the same family member doesn't trust me in the slightest.
Also, my mother has demanded that my fathers parents have nothing to do with us. The locks have been changed and my father given a deadline to cease all contact with his parents or my mother wants him out of the house. This is all happening because they don't consider her part of the family. Who knows if I am.