That's terrible, so sorry to hear about your accident. I wish you the very best and continued health.
Like Weldangrind already said, we'd love for you to stick around and contribute in other ways if you could, but if not, it's completely understandable. There's really no way to 'close' an account.. normally one would just not visit a site anymore if they don't want to be a part of it, for whatever reason. To stop receiving any email from the forum, visit your
User CP > Edit Options > Receive email from Administrators (uncheck that box).
Take care.