net use is the command to connect / disconnect a computer from a shared resource.
Cheatsheet
Help
net use /help
List network connections
net use
Connect
net use [<DeviceName>] \\<ComputerName>\<ShareName> /user:<UserName> <Password> /yes
e.g.
net use z: \\192.168.1.1\share /user:foo bar /yes
Disconnect
- Delete a single network connection
net use x: /d - Delete network connection without a drive letter
net use \\<ComputerName>\<ShareName> /d - Delete all
net use * /delete