How we can I delete a question I asked before at Stack Overflow, which has lots of up votes?
If I try and delete it, it shows this warning:
Sorry, this question cannot be deleted: too many existing answers, or upvoted/accepted answers
Your best option is to plead your case with the moderators - flag the question for moderator attention and write your reason for requesting deletion.
Obviously, it is reasonable to believe that the question will not be deleted exactly for the reasons the warning message conveys. However, if you plead your case with a moderator and the reasons for deletion are deemed acceptable, then a moderator can vote to have it deleted.