Thanks for the responses. I ended up copying the "task" to a text app, and redoing it, then adding it to Evernote as a new note. Good to know about the History failsafe.
I just hit a command key incorrectly and accidentally turned an important note into a task list. I need to undo this ASAP. How do I do this, and how do I permanently disable the Task feature?
I dom't want this mess cropping up on the other computers I use.