So I was about to choose a drive to install windows 10 on, I realized I had other drives there. I deleted them and installed windows on the largest drive.
Should I have formatted the drives before deleting them or it doesn't matter?
The Windows installer will partition and format your chosen installation target drive as necessary. No need to do that yourself. Ideally, just point it at a drive with zero partitions on it and let the installer do it's thing.
So I was about to choose a drive to install windows 10 on, I realized I had other drives there. I deleted them and installed windows on the largest drive.
Should I have formatted the drives before deleting them or it doesn't matter?
Ideally, you should have disconnected all other drives except the one you want the OS on.