Yes, it is possible to reformat your Toshiba laptop's internal hard drive and install Windows 7 using your Windows 7 OEM installation disk. Here's a step-by-step process you can follow:
1. First, make sure you have a backup of any important files and data on your laptop, as the reformatting process will erase everything on the hard drive.
2. Insert the Windows 7 OEM installation disk into your laptop's CD/DVD drive.
3. Restart your laptop and enter the BIOS or Boot Menu. The key to access these menus can vary depending on your Toshiba laptop model, but common keys include F2, F10, or the ESC key. Consult your laptop's user manual or do a quick online search for the specific key to access the BIOS or Boot Menu on your model.
4. Once you're in the BIOS or Boot Menu, navigate to the section that allows you to change the boot order. Make sure that the CD/DVD drive is set as the first boot device.
5. Save the changes and exit the BIOS or Boot Menu. Your laptop will restart.
6. As your laptop starts up, it should boot from the Windows 7 OEM installation disk. Follow the on-screen instructions to proceed with the Windows 7 installation.
7. During the installation process, you will come across a screen that asks you to select the installation location. At this point, you can choose to reformat the hard drive. Select the hard drive that currently has Windows 10 installed and follow the prompts to format it.
8. After the formatting process is complete, follow the rest of the on-screen instructions to continue with the Windows 7 installation.
9. Once the installation is finished, your laptop should restart, and you will have a fresh installation of Windows 7.
Remember to reinstall any necessary drivers and software after the installation is complete, as the Windows 7 OEM installation disk might not have the most up-to-date versions.
Please note that Windows 7 is no longer supported by Microsoft, which means you won't receive security updates or technical support for it. It's generally recommended to upgrade to a newer and supported operating system if possible.
I hope this helps you in successfully reformatting your Toshiba laptop and installing Windows 7!