Dualboot/Bootcamp issues

Two weeks ago I decided to dualboot windows 10 on my iMac 21,5 inch. (Model ID:11,2 i think) mid 2011 running Mac OS Sierra.

I opened bootcamp assistant and only had the option to install the Win support software but not the OS. I played around with the info.plist file and succeeded in what I wanted to do.

I did everything right, but when the download for the bootable USB finished it said that there was no space left on the disk.

After many tries i manually put the windows.iso files on the USB and the windows support software.

The startup disk was there when I rebooted, I clicked on it and the installation was correct. After accepting the terms i couldn't install it on any partition(I had correctly created) so I went online to find a way to fix this and someone in the video, which i can't remember which was it, said to clean disk 0(the whole hard drive) on windows terminal. I didn't know that it would have erased everything, but at least I had nothing important on it.

Windows finished setting up and the first thing I saw was that there was no audio. I later found out that my iMac 11,2 couldn't support EFI boot, but only BIOS.

I found the application rufus that could set the installation to BIOS, but it seems that, since it deleted the mac hard drive, no mac configurations are there, so i couldn't even delete the windows hard drive partition to reinstall Mac OS it via bootable USB.

Now I'm stuck and I can't even factory reset my iMac.

Please answer rapidly I need help.