If a parent is just self-centered or rude, it's fine to edit them from your lives so that you can enjoy yourself. A parent who gets drunk and embarrasses her children in front of their friends or freaks out the grand kids is a good candidate for that. Just being related is not reason enough to put up with someone who is willfully an ass. Forget that.
However, and forgive me if I'm crossing a line, SC has posted about her mom over the years and I get the feeling she has some mental illness issues going on (the pet hoarding from years back, etc) and that's different. I don't think it's ok to oust a parent for being inconveniently unhealthy in one way or another, assuming they're not violent or abusive.