Permanent File Removal
Filter Files/Path from Existing Repo
Dump your repo with:
svnadmin dump /path/to/repo > reponame.svndump
Now you can remove files or a complete path with:
cat reponame.svndump | svndumpfilter exclude --drop-empty-revs --renumber-revs \
/trunk/file-to-exclude.txt /trunk/path-to-exclude > reponame2.svndump
Now create you new repo and load the dump into it:
svnadmin create /path/to/new/repo
svnadmin load /path/to/new/repo < reponame2.svndump