Debian 11 on old Macbook

[frantal@libero.it]

Hello,

thanks for the help and suggestions:

I don't need to press alt (option) to view the operating systems because I have rEFInd installed.

However, 2 Debian icons appear, one OS X, and one Windows.

If I click on the latter, a white writing on a black background appears with: MBR 12: and a flashing underscore.

But I can't write anything.

The Debian 2 takes me to Debian and OS X to the Apple operating system. Assuming I keep the 2 Debian, how do I get rid of the Windows symbol, since it doesn't lead anywhere, so it results useless?

Thanks again

Francesco