How to Delete a Computer Operating System

By Josienita Borlongan

There are several reasons a computer user might want to delete his operating system. He might prefer another operating system and have to uninstall the existing one to replace it. He might be using dual systems and need to delete one of the two. Or he could just like fiddling with the operating system, deleting and reinstalling it again to start with a clean slate.

You have to be cautious in performing this type of operation, whatever the reason for it may be. Here are some tips to ensure that the deletion won't cause any headaches down the road.

Things You'll Need

  • Boot CD
    Operating system (new)
    Back-up disk
    Product documentation

How to Delete an Operating System for Single-Boot Machines

Step 1

Make a copy or backup of important files or programs before proceeding. Saving those important files and folders allows you to access them later on, when you load a new operating system.

Step 2

Install the new operating system. This is probably the easiest and fastest way to remove or delete your current operating system. Insert the new operating system CD and follow the installation prompt. If it asks you if you are sure you want to delete the current operating system, click on \"Y\" or \"Yes.\"

Step 3

Remove the Windows operating system completely by going into \"Safe Mode.\" Try hitting the F8 key repeatedly after the initial bootup. Using the arrow keys, navigate to the Command Prompt (DOS), then hit the \"Enter\" key. When you get to C:\\, type "cd" without the quotation marks, then hit the \"Enter\" key again. You will now be in your local drive directory, or C:\\, where you can type the command DEL WINDOWS (note the space between the words). Then hit the \"Enter\" key again. Click on \"Y\" when it asks if you are sure you want to delete your hard drive. This will then proceed to formatting your hard drive, which deletes the operating system.

Step 4

Install the new operating system using an installation or bootup CD. Follow the prompts to completion.

Step 5

Install the other drivers, such as sound card, video card and CD-ROM.

How to Delete an Operating System for Dual-Boot Machines

Step 1

Start the Windows operating system you want to keep. If you have a dual boot or dual operating system, at initial bootup, it will give you a choice of which operating system to go to. Use the arrow keys to choose which of the two you will keep, then hit \"Enter.\"

Step 2

Determine the Windows folder you want to keep by doing the following steps: Click on \"Start,\" click \"Run,\" type %windir% , then click on \"OK.\" This may show up as \"C:\\Windows\" or any other name on your machine.

Step 3

Do not delete the working Windows folder.

Step 4

Go to the Windows Explorer by going to \"Start,\" clicking on \"Run\" and typing \"explorer\" (without the quotation marks) to find the windows you want to remove.

Step 5

Right-click on the Windows folder you want to delete, then click on the word \"Delete.\" Make sure that this is not your working Windows before you delete it.

Step 6

Click \"Yes\" to confirm the deletion of the second Windows operating system.

Step 7

Go to \"Start,\" choose \"My Computer\" and right-click it. Then choose \"Properties.\" Go to the \"Advanced\" tab; under \"Startup and Recovery,\" click \"Settings.\" This will open a dialog box titled \"Startup and Recovery.\"

Step 8

Go to the \"System Startup,\" then click \"Edit\" to modify the Boot.ini file. This should open a Boot.ini file, which is displayed in Notepad.

Step 9

Save a backup copy of the Boot.ini file before proceeding. To do this click \"Save As:\" on the \"File\" menu in Notepad. To avoid any confusion, save the Boot.ini file with a name \"Boot.old.\" Close this backup copy by clicking on the \"File\" menu, then click \"Exit.\"

Step 10

Re-open the Boot.ini file by repeating Step 8. Identify and then delete the line of text for the Windows operating system that you want to remove from the boot loader. If the second Windows folder you have identified in Step 4 is the Microsoft Windows XP Home Edition operating system, remove the following line of text from the Boot.ini file:

multi(0)disk(0)rdisk(0)partition(1)\\WINDOWS.0=\"Microsoft Windows XP Home\"

Step 11

Save your changes to the Boot.ini file by clicking on the \"File\" menu, then \"Save.\" Then close the Boot.ini notepad by clicking on \"Exit\" or the \"x\" box in the upper right corner of the Notepad. Click on \"OK\" to close the \"Startup and Recovery\" dialog box.

Step 12

Restart your computer. This time, you will only have one operating system at startup.

Tips & Warnings

  • Perform a full backup of your computer prior to performing any deletions to make recovery easier.
    Keep the old operating system's installer CD in case you need to reinstall it in the future.
  • Some deletions are irreversible. Before deleting the operating system, be sure of your decisions.