How to enable and disables usb?

To disable the access to USB port,follow the steps below

1. Click Start, and then click Run.

2. In the Open box, type regedit, and then click OK.

3. Locate, and then click the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor

4. In the right pane, double-click Start.

5. In the Value data box, type 4, click Hexadecimal (if it is not already selected), and then click OK.

6. Quit Registry Editor.

To re-enable a disabled port, follow these steps below

1. Click Start, and then click Run.

2. In the Open box, type regedit, and then click OK.

3. Locate, and then click the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor

4. In the right pane, double-click Start.

5. In the Value data box, type 3, click Hexadecimal (if it is not already selected), and then click OK.

6. Quit Registry Editor.

right click computer icon

select properties

select hardware then device manager

go down to bottom of list open usb

open using the + and right click and select disable the root hubs

do the others as well

but curious why would you want too ?