It is not possible to access the server as “root” user via ftp. If you wish to access the root directory of the server, you can use secureSSH using tools like PuTTY or winSCP. You can configure PuTTY as below:-

1. Download the PuTTy sftp client

2. Open the command line interface :

1. Go to "Start >> Run"
2. Enter "cmd" and click on "OK" button.

3. Go to the directory where psftp.exe is located.

4. Type “psftp.exe -P 2200” to access your server. < Where : is the IP address >

5. Login as root.

C:\Documents and Settings\user\Desktop>psftp.exe -P 2200
The server's host key is not cached in the registry. You
have no guarantee that the server is the computer you
think it is.
The server's rsa2 key fingerprint is:
ssh-rsa 2048 13:fe:d5:d4:43:66:c7:93:03:ed:08:09:ac:e4:95:24
If you trust this host, enter "y" to add the key to
PuTTY's cache and carry on connecting.
If you want to carry on connecting just once, without
adding the key to the cache, enter "n".
If you do not trust this host, press Return to abandon the
Store key in cache? (y/n) y
login as: root
root@'s password:
Remote working directory is /root

6. Use “CD” to change directory and “PUT” to upload files.