If for some reason you want to disable your USB ports, maybe for security reasons, you can do this with a simple registry hack.
- Launch your registry editor, by pressing WIN+R and typing regedit.
- Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor
- Change the value of the start key to 4
- Reboot your machine
Your USB ports will now be disabled completely.