After years of a toxic work environment, I finally decided to move forward in a different lab. However, I have to present an official resignation letter to my advisor (current PI), even when currently paid by a TA position. Any advice on how to do this? I have no idea to make it sound professional and avoid further conflict. I plan to take a leave of absence until I can find another lab.
It can be extremely short and to the point. You don't need to give your reasons:
For personal and professional reasons I've decided to resign my position in your lab.
Nothing more is required as long as your contract, if any, permits it at all. In particular don't say things that might be disputed by others.