Here's a complete guide on how to erase any drive (including USB flash) and make itsdata absolutely unrecoverable usingmacOS.

Selling Your Mac or a Drive? Wipe it Properly and Make Sure its Data is Unrecoverable

When you perform a quick format of, let's say, a USB flash drive, its data is still recoverable if you have the necessary tools at hand. Only the address pertaining to a specific file is erased, not the data itself. This means if your drive falls into the wrong hands, your personal datamay still be recoverable. So, in order to combat this little situation, it's a good idea to perform an extremely low-level format of your drive at hand before handing it over to someone else. Even if they try to recover anything, the chances are extremely high that they'll find anything at all. We will show you how it's done using macOS Sierra, Apple's latest desktop operating system.

Tutorial

Note: Before you begin, it's worth mentioning here that there are going to be multiple read, write and erase cycles. Therefore performing a low-level format on a drive might actually shorten its life and make it slower. So please, do this extremely occasionally or in a moment where you really have to.

1. Connect the drive you wish to wipe in anyany empty USB port on your Mac.

2. Once the drive shows up and is connected, launch Disk Utility. You can either search for it using Spotlight, or find it inside the Other folder in Launchpad.

3. Once Disk Utility is in view, select the drive you wish to wipe from the left hand side.

4. See that Erase tab at the top? Click on it.

5. Here comes the tricky part. Click on the Security Options button. And from here, select the type of security you want. Fastest is quicker but insecure, but Most Secure is extremely slow, but ensures that your files aren't recoverable at all. Make your choice extremely wisely then click on OK.

6. Once the process kicks off, you have to be extremely patient since it takes a considerable amount of time if you have opted for the Most Secure option.

It's best to take this time to reflect back on your life, grab a cup of coffee, join a gym, walk your dog or maybe consider buying a cool new gadget for yourself. Trust me, it takes a lot of time to complete.

But hey, in the end you will be left with a drive that has no trace of any of your data at all. How cool is that?