Do you know the licence key for the win 8 install?
If yes, then install win 10 and use the win 8 key.
If no, might want to run 8 and get the win 10 update via windows update or just download win 10 here and choose option one.
Windows 10 media creation tool
Preloaded copies have the key already installed so you may need to take this one extra step to make sure it activates in win 10.