If you originally purchased a digital copy from Microsoft using a Microsoft account, log into account.microsoft.com/services . Go to "Order history" and look back to 2010-2015. The download link may still appear, but Microsoft has been pruning legacy titles.
Uninstall all Office, OneDrive, Skype for Business, and even old Visual Studio Office tools. Reboot. Use the Microsoft "Fix it" tool (SaRA.exe) to scrub leftover registry entries. download office 2010 professional 64 bit