Previous Windows Installations

[anon(9099462)]

I ran Disk CleanUp on my Surface Pro 3 after installing Windows 10 and I see that there is 17.3 GB from previous Windows Installation and 4.04 GB from Temporary Windows Installation Files. If I want to gain that space back what should I do move the files to a USB or is it safe to remove it all? I would like to see some suggestions. Thank you in advance.

 

[three_thoughts]

I'm wondering the same thing

Pretty sure I can delete the Windows.old folder (assuming I don't need any of the personal files that are duplicated in there)?
Can I also delete the $Windows.~BT and $Windows.~WS folders?