Is it a good practice to delete your own answer, if it's not upvoted?
Sometimes someone has rephrased my answer. Sometimes it is correct, but users consider it irrelevant.
If the other person's rephrased answer is better, is technically correct, and covers the same ground, then I'd definitely consider deleting an answer. However, I'd never delete an answer just because it didn't get any upvotes. And if it's technically correct and addresses the question, I won't delete it if it a gets negative score - a lot of SO users vote on the basis of what they WANT the answer to be rather than what it actually IS.