How to completely wipe a pc 100% before selling it?

This is a very important task when you are going to see or trade-in the old PC. To completely wipe a PC before selling it, follow these three essential steps:

First, back up any personal data you wish to keep to an external drive or cloud service. This is a critical one-way step; once the wipe begins, there is no recovery. Ensure you've transferred documents, photos, licenses, and any other irreplaceable information. Also, deauthorize and sign out of all software and services (like Microsoft Office, Adobe apps, Steam, etc.) and note down your Windows product key if it's not digitally linked to your Microsoft account.

Second, perform a full factory reset using built-in tools, but choose the correct options. In Windows, use "Settings > Update & Security > Recovery" and select "Remove everything." Crucially, when prompted, choose the option to "Clean the drive" or "Fully clean the drive." This process overwrites the data, making it much harder to recover, unlike the quicker "Just remove my files" option which only deletes pointers.

To 100% wipe a computer, especially on older PCs or if the built-in tool isn't available, use a dedicated disk-wiping utility. Boot from a USB drive running a tool like DBAN or the secure erase feature in your SSD manufacturer's software. These tools perform multiple overwrite passes, meeting stringent data sanitation standards. After the wipe, reinstall a fresh copy of Windows from Microsoft's media to provide the new owner with a clean, ready-to-use system.