Reclaim 400GB from Boot Camp partition on MacBook

francheska210 wrote:

ohh, well i didn't get to ask him how'd he do it but i think he transferred his files to his other mac since he got a brand new one

Start at Step#5 in the Apple article @Zuraczurx linked originally since it appears your uncle already erased the macOS partition. You will want to use Disk Utility to erase the whole physical internal SSD which will destroy all existing data & partitions on it. If you have any personal data on the macOS volume, then make sure to back it up before erasing the system.

I highly recommend you first create a bootable macOS USB installer now while you still can so you have more options available in case you have issues using Internet Recovery Mode to reinstall macOS.

Hopefully if your uncle used his AppleID on this laptop that his AppleID from being associated with this laptop or you may encounter issues down the road.

Take a look here: Remove Windows from your Mac using Boot Camp - Apple Support

You'd be better off getting your uncle to clear the Mac and prepare it for gifting. Otherwise, if you ever have problems and need to restore it then it will be Activation Locked and only your uncle will be able to fix it - assuming he remembers his ID and password.

What to do before you sell, give away or trade in your iPhone or iPad – Apple Support (UK)

Did he clear it using the method in the link I posted or just delete his stuff from it. If he didn't use the method in the link then you could have problems down the line because he will still, effectively, be the owner of the Mac.

Like I said, if he didn't prep the Mac as in the link I posted before then you risk problems in future. I'm not going to say it any more.