We do not delete individual builds on CircleCI.
I accidentally dumped my secret/passwords into my build
After exposing sensitive information, it is too late to ensure the security of these secrets or passwords. Please practice good security hygiene and rotate any keys or passwords that may have been exposed. That way, these leaked secrets cannot be used.
Environment variables and Contexts do have secret masking enabled by default. More information on this functionality can be found on this blog post.