rm on cygwin, cannot unlink not owner

Solution 1:

If you are the adminsitrator on your machine, ownership is a concept that shouldn't concern you much.

Do chmod u+w .svn, then try your remove again.

Solution 2:

super-user (root) is the only account able to use rm -d flag

From the rm man page

-d, --directory

      unlink FILE, even if it is  a  non-empty  directory  (super-user
      only; this works only if your system supports ‘unlink’ for 
          nonempty directories)

You will need to su root or something similar before using rm -d

Have you tried rm -rf /full/path/to/dir or (if empty) rmdir /full/path/to/dir ?