I have a number of commercial flash drives with outdated information. Is it possible to unlock them, erase the data and then re-use them?
Increasingly, companies are putting data on cheap USB flash drives and passing these drives out to customers and colleagues. The good news is, you can re-use them. The easiest way of doing this is simply to plug the drive into your Mac, select its contents (C-A) and transfer the old files to the Trash. Remember to empty the Trash after (Finder➝Empty Trash). This not only saves you having to reformat the drive, but also provides you with the space you need to copy your files.
If you can’t delete the files (perhaps because they’ve become corrupted), launch Disk Utility (in /Applications/Utilities), select the flash drive from Disk Utility’s list of drives, click on the Erase tab, choose MS-DOS (FAT) from the Volume Format pop-up menu, and click on Erase. The drive will be erased and automatically reformatted.
The advantage of using the FAT file system (File Allocation Table) is that it lets you use the drive with both Macs and PCs. The disadvantage is that you won’t be able to write files larger than 2GB to the drive, because 2GB is the size limit for the MS-DOS (FAT) format. If you need to copy larger files, such as big images or videos, you’ll need to format the drive in the Mac OS Extended (Journaled) format.
To do this, you’ll first have to select the drive in Disk Utility, then click on the Partition tab, select Partition from the Volume Scheme pop-up menu and click on Options. Choose GUID Partition Table or Apple Partition Map from the resulting sheet (GUID for Intel Macs or any Mac running OS X 10.4 or later, and Apple Partition Map for PowerPC Macs running any version of OS X), and click on OK. Choose Mac OS Extended (Journaled) from the Format pop-up menu and click on Apply. In the sheet that appears, click on Partition, and your flash drive will be formatted as a Mac OS X Extended (Journaled) drive.