I submitted the correct essay in an exam, but I did not remove my draft outline at the beginning of the essay. Is it going be a problem?
Probably not.
But there is really only one person that knows for sure: the professor in question. So, as Mark Meckes already mentioned in the comments, send them a message, explain that you forgot to remove the draft outline at the beginning of your essay and ask them to ignore that part, and to exclude it from the word count limit if applicable.
Be aware that you might not get a response if the professor is busy, which doesn't mean there is a problem.