I have lots of experience with this. I try to practice detaching with love. I don't think anyone is inherently toxic. In my experience most relationships that reach "toxic" levels are because there are unspoken expectations that the other party feels guilty about not meeting which creates a dynamic of resentment and obligation. If I draw clear boundaries, stick to them and am 100% honest about what is and isn't working for me in the relationship / situation, the "toxins" dissipate. Often times there is strong reaction to boundaries (esp with family) that may create a distance but ultimately if you keep the focus on yourself and act with integrity, you've done all that you can. All relationships are 50/50 and sometimes we don't have a choice on who we engage with. We don't all have the same goals and intentions so exposing that can be freeing.

Alternatively, if you are interested in "removing" them, it's always an option. If I nourish the relationships that move me fwd and put less energy into the ones that don't work for me or am honest about why they aren't working, they either adapt or fade away.

This book Crucial Accountability http://amzn.to/1nwYG2C might help too. They also wrote a book Crucial Conversations. Hope that helps, happy to chat more if you need more specific advice.