Jenkins before 1.551 and LTS before 1.532.2 does not invalidate the API token when a user is deleted, which allows remote authenticated users to retain access via the token.
https://wiki.jenkins-ci.org/display/SECURITY/Jenkins+Security+Advisory+2014-02-14
https://github.com/jenkinsci/jenkins/commit/5548b5220cfd496831b5721124189ff18fbb12a3