To unshare a local USB port, please, follow these steps:
Switch to "Share local USB devices" tab at the application's Toolbar:

In USB devices tree select the USB device you want to unshare:

Click "Unshare USB device" Toolbar button, or select "Share devices" --> "Unshare local USB device" option from the Main menu:

Once the device is successfully unshared, the icon in USB devices tree will be changed to
, and you will gain full control of the USB device.