When you delete a file, macOS removes the reference to that file, but doesn't delete the actual data that made up the file on your hard drive. Over time, this data will be overwritten as macOS writes new files to that area of the drive.
This means that, given the right software, someone could reconstruct all, or parts of files that you've deleted. For privacy and security reasons, you can set CCleaner for Mac to wipe the free areas of your hard disk so that deleted files can never be recovered.
Note: This process should not be used on any solid-state drive or other Flash-based storage. For more information, please look here.
Note: Wiping free space can take several hours, or even longer depending on the size of the drive, the number of passes selected, and the speed of the computer.
To wipe your drive using Erase Freespace:
- Click Tools, and then click Erase Free Space
- Select the volume whose free space you want to erase
- Choose the type of security you require (see here for more information about erase methods)
- Click Erase Free Space
- You will see a warning message. Click Yes to proceed.
Wipe Free Disk Space limitations
CCleaner for Mac can't wipe every deleted file from your free disk space. There are some limitations, because of the way macOS stores some files. Here are some examples:
- The file has already been overwritten by another file
- The file was created almost exactly when you ran CCleaner