I didn't have it in my budget for a new hard drive so I am using my old one. I am wondering if I can just put it straight into the new system and use my windows 10 usb boot drive to fresh install windows 10 on it, will that destroy all the old drivers/files/information on the hard drive? I'd like it to as I'm aware of the OS issues if you keep an old OS/drivers.
When you start the Install process, look for an option to Delete any Partition already on the HDD unit. Delete ALL of the Partitions so the drive is completely Unallocated Space. Then start your Install.