It looks like there were some slight issues with that BA. The person who selected it tried to unselect it; most likely they were trying to quote them and misclicked. That BA then refused to be unselected, probably because it was the OP's own post. After closing and re-opening the thread, it seems to have resolved itself and the thread is no longer marked as "Solved".
Not at all. Those kinds of mistakes happen quite often with new users who aren't familiar with the forum system. Feel free to unmark it, especially since it is your own post and it is clear that the thread is not solved.