### **For Windows:**
1. **Backup your data:**
* Before formatting, save your important files to an external drive or cloud storage such as Google Drive and One Drive.
2. **Create a Windows Installation Media:**
You need to have a bootable USB drive with Windows. For that,
- First download **Windows Media Creation Tool** from the Microsoft website.
- Then follow the steps in the tool to make a bootable USB drive with Windows.
3. **Booting from the USB:**
Insert the prepared bootable USB into the laptop.
- Restart the laptop and boot into **BIOS/UEFI ** by usually pressing a key bound like `F2`, `F10`, `Delete`, or `Esc` during the boot process.
Change the boot order to put the USB drive first in the list and reboot.
4. **Begin Windows Installation:**
If all goes right, the laptop will start off by booting from the USB, and it will begin to install Windows for you.
Select a desired language and region settings, then click on **Next**.
- Click **Install Now**.
5. **Delete Partitions and Format:**
- You choose **Custom Installation**.
- Inside, you will be presented with a list of drives and partitions. Every partition listed here should be deleted. Windows will create those that will actually be needed in the process.
- You then click **Next** on the unallocated space.
6. **Reinstall Windows:**
The installation process will start; Windows will format the drive, and a fresh copy of the OS will be installed. Follow on-screen instructions for completing the installation and setting your preferences.
### **For macOS:**
1. **Backup your data:**
- Make a backup with the **Time Machine** or copy all your important files to an external drive or cloud storage.
2. **Restart in Recovery Mode:**
- Immediately press and hold **Command ⌘ + R** while booting the laptop to enter Recovery Mode.
3. **Erase the Disk:**
- Open **Disk Utility** in Recovery Mode.
- Then click on your main startup disk; it's usually labeled as **Macintosh HD**. Next, click **Erase**.
- After selecting the correct format for your Mac ('APFS' for newer ones, 'Mac OS Extended (Journaled)' for older ones), confirm the erase.
4. **Reinstall macOS:**
- When the disk has been erased, close Disk Utility.
- In the macOS Utilities window, select **Reinstall macOS**.
- Continue through the on-screen instructions to begin installation of the OS.
5. **macOS Setup:**
- After installation, set up the Mac to your preference.
### **Final Steps:**
- **Install drivers and updates** to Windows by using **Windows Update** or to macOS by using the **App Store**.
- Restore your previously backed up files.
