I have a file in my Clearcase repository. I checked it out and modified it, and then checked it back in.
I haven\'t done anything like make a baseline, or rebase, o
Clearcase can do much better than just making a new version where you undo the change! Open the version history on your file, find the version you mistakenly checked in, and destroy it (select version to destroy and find the appropriate command under the Versions menu). This is what rmver does too, if you want to use the command line. As VonC said your this destroys your mistake irretrievably. I'm not seeing a downside to that.