If you mean that you want to prevent a particular computer from accessing "shared" folders and printers in other computers on the network then:
1) In the network adapter properties, disable or uninstall:
- Client for Microsoft Networks
- File & printer sharing for Microsoft Networks
2) In the Firewall settings for the other computers, remove permission (the IP address) for access by the restricted computer.
If the particular computer doesn't need a LAN connection for internet access, then the simplest solution is to remove it completely from the network.