Hi Filomena,

Restricting access on a revision basis is not possible.
You can remove old versions or part of your repo by using the dumpfilter command.
1. Dump your current repo
2. Use dumpfilter to filter unwanted elements
3. Reload filtered dump into a new repo.
Doc: http://svnbook.red-bean.com/en/1.7/svn.ref.svndumpfilter.html
Exemple 1 - Removing old revisions: http://robmayhew.com/delete-parts-of-subversion-history/
Exemple 2 - Removing a directory: http://www.lesnikowski.com/blog/index.php/how-to-permanently-remove-svn-folder/


2011/10/23 Nico Kadel-Garcia <nkadel@gmail.com>
On Mon, Oct 10, 2011 at 12:28 PM, filomena ciola
<ciolafilomena@gmail.com> wrote:
> Hello,
> Please I need your help for a little question:
> I need to erase all the old revisions, if it' s possible, how can I do for
> make this automatically? if this isn't possible, can I put a pw so only
> authorized personell can see old revision?
> Thank you for your interesting
> With best regards
> Mimma Ciola

If they can see the file, in Subversion, they can see all the old
relevant revisions from that repository. They may not be able to see
*other* files if you have access to them blocked in Apache or svnserve
managed access.

It's also vaguely feasible that if you used svn+ssh based access, the
relevant "svn" user could be made not a member of the appropriate
groups to see that old revision at all.  But this would get *nasty*,
very quickly, It would be like replacing the command "rm" with
something that moves files aside. It would work until it broke,