I tried to find any feature seems like 'rename' both on server side and client side but failed, is it possible?
1) Check in the project & make sure no-one is using it. Probably a good idea to stop the server.
2) Back up the repository
3) On the server, rename the root project directory to your new name
4) Start the server again, and on the client, check out using the new name.
Do all this at your own risk - I've only tested it with a local filesystem.