An operating system can delete itself

Windows Uninstall Windows completely - this is how it works

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If you sell your computer or want to switch to another operating system, you should completely delete Windows beforehand, including data and boot manager. It's basically very simple, but it takes a few steps.

Delete only Windows

If you only have a single Windows on your computer, you basically can't go wrong - except for forgetting to make a backup! So before you start, back up all the data from your system hard drive to a second internal / external hard drive, depending on whether you want to use the computer later or sell it, for example. In this guide we will explain to you how to create a backup with Windows 10. The actual deletion of Windows is quite simple: you start the computer from a CD, remove the Windows partitions and ultimately overwrite the hard disk.

First of all, you need one matching live Linuxthat starts from USB or CD and brings the right tools: PartedMagic is available as the (last) free version from heise Download: https://www.heise.de/download/product/partedmagic-92431. Either burn the ISO file to a CD / DVD or use the Unetbootin program to boot from a USB stick: Simply select the option "Disk image", there the downloaded ISO, your inserted USB stick as"Drive"and then start the copying process. Then boot from the new data carrier.

Note: The free version of PartedMagic, which was once available from heise Download, is no longer available. Alternatively there is the paid PartedMagic full version or the free open source software GParted.

Tip:Windows 10 does not restart completely via the start menu, which is why booting from external media may not work. But you can use Windows in the command prompt ([Windows] + [X]) actually force you to restart properly. Just give the command "shutdown / r / f / t 0". This will restart Windows (/ r), which in turn will be forced (/ f) and the whole thing without a time delay (/ t 0).

In rare cases the computer does not start from the inserted boot medium. Then you have to Change the boot order in the UEFI / BIOS. You can get there by pressing the [DELETE] press, with some manufacturers it could also [ESC] or something else - this will also be displayed on the screen (even if only very briefly). In this article we will explain to you which key you have to press for which manufacturer to open the BIOS / UEFI. In the BIOS / UEFI, more or less the firmware of the computer, you then have to search for the Boot settings and after the sequence search. Unfortunately this is not the same for all systems. Alternatively, on many devices you can use [F12] a Call up the boot menu and start it manually from the USB stick. Starting from a CD / DVD should work on all systems without further intervention.

After starting GParted, start the "Partition Editor". If several hard disks are installed, you still have to find the right one in the top right: Under Linux the hard disks are called hda, hdb and so on, and SSDs and USB storage devices are sda, sdb etc. As a rule,"sda"be the Windows hard disk. Now delete all Windows partitions using a Right click - Usually these are a large NTFS partition with Windows and a small NTFS partition with the note "System-reserved" for Windows' boot options. If you have an additional, pure data partition, you can of course keep it as long as the computer stays with you. Then click on "Apply"to implement the settings. Optionally, you can repartition and format the empty area again beforehand.

Quit the editor and start the entry "Erase DiskWith the Disk Eraser you can overwrite entire hard disks or partitions with zeros or random values ​​so that data cannot be restored. For entire hard disks you can simply use the first menu item (“Disk (External)”) and for partitions the second (“Part (External) "). In both cases then select the desired destination, confirm a Warning message and let the program write. After that, Windows and all data are gone.

Delete dual boot Windows

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It looks a little different with dual-boot systems. If you have a Linux running in parallel, start the program "gparted"- the" Partition Editor "from GParted - and carry out the same steps as above. Since you obviously want to continue using the computer, you can save yourself overwriting the data. If you still want to overwrite, you have to install a deletion program, for example "nwipe", which works in a similar way to the in-house tools.

If you have installed a second Windows in parallel, you can simply use the Windows control panel: Under "Control Panel / Administration / Computer Management" find the "Disk management". As in GParted, you can delete the partition of the superfluous Windows here. There is no second, small boot partition, because the computer only needs the boot information once. If you delete safely under Windows, that is, overwrite it use the Eraser program to do this.

Repair boot manager

It can happen that a boot manager still refers to the old system after removal - of course only with dual-boot systems. Although this does not prevent a correct start, it is annoying, may require you to manually select the system to be booted and definitely costs a little time. So you should rewrite the Windows or Linux boot manager or, in the case of Linux 'Grub, simply update it.

If you have worked with a system with two Windows versions, you can use the EasyBCD tool: In the "BCD installation / MBR configuration options"find the option"Master Boot Record"(MBR) to be completely rewritten, which should fix problems.

If a Linux system is left over, you can also set up the boot manager Grub again here in order to destroy any Windows leftovers in it. To do this, open a terminal and enter the command "sudo update-grub" a.