Seagate Drive in BIOS but can't see it in file manager

I installed a Solid State Drive as my boot drive earlier this week. It works fine. I want to use the 2TB Seagate that came with my Inspiron 3847 as a backup (slave)drive and I also want to take Windows 10 off of it. I can see the drive in the device manager (drive 1) and in BIOS (SATA 2), but I can't see it in the file manager so I can reformat it. This particular model (ST2000DM001-1ER64) has no jumpers to set it as a slave drive. Seagate says it's automatic. I'm stuck as to how I resolve this. Any help is appreciated. Thanks!