You can easily disconnect the YouView app from your box using the Settings option in the main menu of the app. In this option you can find a dedicated button allowing you to Disconnect your YouView box. If you go back into settings after doing this, the button will offer you the option to Connect to YouView box. Pressing this will start the connecting process again.
Please Note: If you have reset your box through Maintenance Mode or the YouView settings you’ll need to disconnect the app from your box and re-connect.
You can also disconnect the app by un-installing and re-installing the app from your device.