Try using the disc cleanup utility. Mouse pointer to bottom left, right click the start icon, select 'run'. Type or copy and paste cleanmgr in the open field. Click ok. In the pane that opens select your drive, usually (C:). Select ok. It will show all the files to be cleaned. Select ok after you've browsed the files list. Most probably Windows Old file won't show the first time. Run cleanmgr again and this time windows old should show so tick the box. Select ok. As it's a fresh update you won't need to check the old folder for documents, etc, before removing.
Surface Pro 5 News - release date, UK price, features, specs