Versions represent previously-checked-in editions of a build configuration. You can do only certain things with previous versions:
You can view previous versions of a build configuration, as described in Viewing Build Configurations.
You can copy previous versions of a build configuration, as described in Copying Build Configurations.
You can rollback to a previous version.
You can rewrite the current build configuration so that it is identical to a previous version.
You cannot delete a previous version.
For information on how to rollback or rewrite, see Versioning.