Ubuntu 18.04 LTS and Windows 10 - DUAL BOOT. How I can delete Windows 10 without unistalling Ubuntu partition necessary for boot?

Asked by Piotr on 2021-03-24

Dear Ubuntu Community,

I have problem. I contacted with friend and suggested him to install Ubuntu. He installed Ubuntu 18.04 but he didn't unstall Windows 10 and now he have dual boot option in GRUB. He asked me about deleting Windows but I don't know if he format Windows partition Ubuntu will start or some information for booting can be in Windows partition? How I can check this and safe delete Windows?

Can you help me?

Yours faithfully,

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If you dual boot then GRUB will be managing the boot up. I suggest you make a final full backup of your data just to be sure.

If you are using UEFI (Likely) then I'm not personally sure but if not then you can simply delete the Windows partition and create a new Ext4 partition for your data. If you have used LVM for your partitions then you can add the new empty disk to the volume group to extend it.

Personally I'd just wipe the entire disk and reinstall with Ubuntu 20.04 so there are no remnants of Widows around the place. It'll be easier and much cleaner.

Maybe someone else can advise on the UEFI stuff....

Piotr (peterq94) said : #2

My friend use Legacy Mode so it is old BIOS, non UEFI. So he can delete Windows partition and Ubuntu will boot up normally?

Yes due to no UEFI participation. Do a backup before doing anything though. You can always boot to Ubuntu USB stick and reinstate GRUB if needed

Piotr (peterq94) said : #4

Can I reinstall only GRUB without reinstalling system if his system will be broken after deleting partition with Windows system?

Yeah you can boot to the live CD / USB desktop of Ubuntu and reinstate GRUB

Piotr (peterq94) said : #6

Okay, I have one question. Everyting needed to booting my system and starting Ubuntu is in this directory --> /boot ?

Yes to start the process, yes

Piotr (peterq94) said : #8

I did this today and I had trouble. After formatting two partitions from Windows everythings works fine but when I decided to delete two partition to make one bigger after reboot Ubuntu was deleted (I mean that my PC can't find Ubuntu system). I founded that this was problem with finding partition for Ubuntu (SWAP, /home and root /). In live usb I founded this partition easily so this was bug. I used GNOME Disk utility so this was problem with this program. In the future I will do this with terminal. What is the best program on Ubuntu by deafult to manage my disk (partition, formatting)?

Piotr (peterq94) said : #9

Thanks actionparsnip, that solved my question.