Undo an SVN commit

Assuming you are in the svn working directory, find the version you want to undo, let's assume it is version 6411 now run

svn merge -c -6411 .

which will undo the change and put the reverted version into the working directory, then you just need to commit the change.

The revision MUST be negative to undo a change and the . is just the working directory path.