This is answered at the StackExchange bounty FAQ. If a user account is deleted with an outstanding bounty, then the Community user becomes the bounty owner, and the points are eventually awarded following the "no intervention" rules.
You can find links to some basic information about bounties in the corresponding tag-info.
These two points from the faq item How does the bounty system work? are relevant:
You must have at least 75 reputation to start a bounty, and at least as much reputation as the bounty amount.
If you have already answered the question before, the minimum ...