How can I install macOS on the second hard drive inside a computer? I just bought a 2011 Mac mini which has two hard drives inside. One of the hard drives had a Mac Recovery I was able to transfer my data to with Time Machine, the other one is called &quot;Windows&quot; so I'm assuming it's formatted differently.

Can I format the Windows drive to install a Mac system on it without opening the computer?
Edit: After reinstalling twice, I am not sure there is a second hard drive inside the Mac anymore. I updated the question here. I will edit further this question once I understand what is going on inside this machine.
Yes, you can. You should 1st check if you can read the windows disk. If so, make sure there is nothing on it you want. If you don't care what's on it skip that and go to disk utility. Using disk utility you can erase the windows disk and reformat it in a format you want. Then you can load the Mac System on the disk.