It can be very complicated or quite simple. If you have not made any personal guarantees for company liabilities, you can have the operating agreement amended to reflect that you are no longer a member. If you did make personal guarantees, its going to be complicated. You need to get the creditors to release you of your guarantee. The can be done by substituting another person's guarantee for yours, or satisfying the debt.
Disclaimer: I am not offering legal advice, assume I do not know the law in your state and that I am just making suggestions for starting points for when you do speak with an attorney. Do NOT rely on anything I write and contact a lawyer in your area immediately after reading my posting.