HOW TO WIPE YOUR DRIVES
To properly wipe a hard drive you should boot into a live linux USB or live cd. Once you have booted into a linux distribution, you can use the fdisk command to find your hard drive name and dd to wipe your drive with random data and zeros. In addition to this we will also cover how to use ATA secure erase which is an extra way to wipe your drive that you should use in addition to manually overwriting data.
When you boot into your linux OS you should open up a command line interface such as the terminal application. You will type the following command.
sudo fdisk -l
This command will list your hard drives and external media. You will locate your drive by the size of the volume. The average hard drive will likely be named /dev/sda. in this case the commands to wipe would be
sudo dd if=/dev/urandom of=/dev/sda status=progress
sudo dd if=/dev/zero of=/dev/sda status=progress
I would do two passes even though technically it has not been proven that you can recover reliably even after 1 pass. I would not take a gamble and use two passes in addition to secure Erase tbh just in case. I feel the same way about things like Qubes combined with Whonix.
If you are going to use Tor Browser, you might as well combine it with Qubes and a whonix virtual machine because that little bit of extra effort will help you out a lot by not allowing you to make as many mistakes. Everyone makes mistakes but one thing Qubes will do is help you compartmentalize things automatically so that you do not have as much of a chance of human error.