You can lock directory with a password by using cpanel "Password Protected Directories" option.


1. Log into your cpanel account.
2. In the "Security" section, click on "IP Blocker" Icon.
 

3. Under "Add an IP or Range" you should enter the IP Address .block.
.. "Add" button.


Here is Example:
Single IP Address: 192.168.0.1
Range: 192.168.0.1-192.168.0.40
Implied Range: 192.168.0.1-40
CIDR Format: 192.168.0.1/32
Implies 10.*.*.* -- 192.