You can format the drive...or delete the windows data off it and keep it as a data drive (if you have many pictures, much music or videos, many games, etc.) if you need space. Alternately, use it as a backup drive. Regardless, I'd keep it for a month to ensure the new drive doesn't blow up...if it is going to, it is most likely to go out within a month*.
Is your windows 10 install retail? Otherwise, you may have trouble clean installing.
Good luck!
-
*i have no support for this statement, but have had a few devices stop working within a month of purchase...after that the risk of failure seems to drop for a while.