There are at least two options:

1. You can reverse the change set, as you mention. One way to do this from the Eclipse client is:
  a. Right click on the owning component in the Pending Changes view and select Show->History. The change set will appear in the History view.
  b. Right click on the change set and choose Reverse. This will create a new change set which is the reverse of the original.
  c. Deliver this new change set.

2. Alternatively, you can really remove the change set from the stream you delivered it to. You can do this by discarding the change set from your local workspace and then replacing the content of the stream with the content of your workspace for the particular component that's affected. This is a more risky solution, because it *really* replaces the content of the stream with whatever you have in your workspace...  it will remove anything in the stream that you don't have in your workspace. To do this:
  a. Accept any incoming changes from the stream you are working with (to prevent losing anyone else's work).
  b. Right click on the owning component in the Pending Changes view and select Show->History. The change set will appear in the History view.
  c. Right click on the change set and choose Discard... This will discard the change set from your workspace. So your workspace should now have all change from the stream *except* the one you want to remove. You can verify this by checking that your bad change set is the only thing you see Incoming.
  d. Right click on the component and choose "Replace in [your stream name]..."


Hope this helps.