Why do you want to remove the last revision? Does it contain data that may be sensitive in nature, and should never be seen by anyone, or was the last revision a real stinker?
As pointed out, you can do a dump and load via svnadmin
. It takes your repository down and is usually more of a pain than it is worth. However, it does make it seem as that last revision never took place. It's the only way to completely rub out the revision. Something you might do only when information in that revision is something that's very proprietary or something that could get your company sued.
An easier way is to simply revert that bad revision. You can revert the last revision (or any revision) via the svn merge
command:
$ svn merge -c -$rev_to_remove .
The old removed revision's history will still be there, and it will be accessible if a user knows Subversion well enough. But, the state of the repository will be back where it was before that last fatal revision.