Can someone die from sever iron deficiency/anemia? specifically in the case if an eating disorder?

Absolutely: Severe anemia from any cause can throw you into congestive heart failure and then pneumonia. Iron deficiency has many causes, including fad / politically correct diets, but also bleeding from some source that will need to be discovered. And being anemic is miserable in itself, preventing you from working and playing to capacity.

Probably: Anemia of any kind can be life-threatening. In eating disorders, diets can become deficient in any number of vitamins and nutrients, iron included. The problem in anemia is that your body can't deliver enough oxygen to your brain and other parts. Ultimately, this can be fatal. Be careful and consult your physician if you have questions.