remove unused file

packages/app/src/server/routes/logout.js

@@ -1,11 +0,0 @@
-module.exports = function(crowi, app) {
-  return {
-    logout(req, res) {
-      req.session.destroy();
-
-      // redirect
-      const redirectTo = req.headers.referer || '/';
-      return res.safeRedirect(redirectTo);
-    },
-  };
-};