In Talend Studio Repository tree view, click the Route Designs>Routelets node to expand the Routelets tree.
The same way as for the Routes, you can create folders via the right-click menu to gather together families of Routelets. Right-click the Routelet node, and choose Create folder. Give a name to this folder and click OK.
If you have already created Routelets that you want to move in this new folder, simply drag and drop them into the folder.