Click the icon in the lower part of the window (network or wired network or wireless network , depending on the type of network detected) to open the Devices in my network window.
In the My Network section, click the Devices in My Network link.
In the Devices in My Network window, select the device that you want to disconnect.
In the right part of the window, find the MAC address of the device.
Block the device MAC address in your browser settings. Visit the website of the specific vendor to view the User Guide for your router.
After the MAC address is blocked, the device will not be able to connect to your network.