How do I remove bundles from a p2 mirror?

I've created a p2 mirror as described in various places:

• http://wiki.eclipse.org/Equinox/p2/Ant_Tasks
• http://wiki.eclipse.org/Equinox/p2/Ant_Tasks/Partial_Mirroring/Example
• http://ramblingabout.wordpress.com/2009/06/23/naive-scripts-for-mirroring-p2-repositories/

I've filled it with the bundles for Eclipse 3.7. It now contains stuff like ECF and the C++ tools which I won't need.

What is the best way to clean those from a repo? Can I remove them at all or do I have to run the mirror script again using a partial mirror?

You can use p2.remove.iu Ant task. Look for this and other useful p2 repository tasks here.