If you want to delete the unnecessary files and the previous windows files from your Windows 10 system follow these simple steps.
Select settings from the start menu or search settings in the search bar then select settings from the list.
Now click on the System menu from the listed items.
Select Storage from the left menu.
Now you can see the total storage of your system and used spaces etc. Next click on the Temporary Files.
Now the system will scan for the files. After scanning the system will shows some deletable files in the list. Now you can select whatever files you want to delete from the list and then click the Remove files button on the top.