If I delete my answer with some up votes, do I lose the reputation? Or, if I delete an answer with down votes, is negative reputation negated?
In the past you would lose (or regain) all reputation due to a post being deleted, but this has changed in March 2012.
There is now an exception to the rule that votes are reversed at the time of deletion and that is to reward content of "lasting value" as follows:
First, if you’ve contributed something worthwhile to the site, you should keep the reputation for that even if it eventually gets deleted. “Worthwhile” here is defined as,
- A score of 3 or greater
- Visible on the site for at least 60 days
In fast-changing professions, there should be no shame in contributing valuable information just because it eventually goes out of date – and there shouldn’t be a penalty for deleting it when it does. Naturally, editing to bring an answer up-to-date is preferable – but if someone else already posted a good answer with current information, you should be able to remove yours and keep the reward for the time it was useful.