Simply commanding your computer to delete files does not guarantee the file cannot be recovered. In many instances, file are only delisted from the file record and left as-is until finally written over by another file. Professionals and users with basic training, if given the opportunity, can easily recover delisted files.
Don't take a chance with your deleted files and throw-away hardware. Take steps to delete unwanted files permanently from all forms of storage media and rest easy.
Deletion on different types of storage drives
Most users consider the deletion of files to be a simple, consistent process across all platforms. Unfortunately, the type of drive that you own or use plays a large part in the status of files after deleted.
- Solid State Drives (Internal) - Solid state drives (SSD) are designed to operate best when writing to empty sectors. To facilitate this process, drive manufacturers created a protocol called TRIM, which automatically erases files designated for deletion and leaves sectors empty. In most situation, data deleted with the TRIM protocol cannot be recovered.
- Solid State Drives (External) and other removable media - SSDs that are external to an operating system will not get the benefit of the TRIM protocol. This means that an external SSD is just like any other type of removable media, like USB flash drives, and will have to be manually wiped to remove any record of previously deleted files.
- Mechanical Hard Drives - Mechanical hard drives are the old-school storage media that most users are familiar with. Mechanical drives are still installed today alongside SSDs are a form of large-media storage to keep from over using the limited write-cycles of the SSD. Files stored and deleted from a mechanical drive can be recovered as long as that sector has not been overwritten by a new file.
Wipe free drive space on a drive
If you aren't interested in starting from scratch by reformatting your entire drive just to guarantee the deletion of a few files, you will have to use a 3rd party program that can wipe the free sectors of all data.
A simple to use a free program, like CCleaner, can be a simple to use and useful tool for completing your permanent file deletion. However, the free programs are normally limited to cleaning free space only. If there are files you have forgotten about or that have been mislabeled and stored in the wrong location, they will still be recoverable once deleted unless the free space wipe is run again.
Wiping external drives and storage media
The only way to guarantee all deleted file are unrecoverable on an external drive is to format the entire drive. It is possible to perform the same free space wipe that CCleaner provides, but you come up against the same issues as previously mentioned. If you are planning to throw an old external drive away, selling it, or giving it to a friend you should perform a full format.
The process to format an entire external drive is simple. First, connect the external drive to your computer and then open Windows Explorer or File Explorer. Next, right-click on the drive's icon in explorer and select Format from the menu. Be sure to uncheck the Quick Format selection in order to perform a full format and fully erase all files.
For another option, CCleaner provides a drive wiping tool as well. You can locate the option to wipe a drive by selecting Tools and then Drive Wiper.
The nuclear option
In most cases, the options listed above are more than adequate for permanently removing deleted files.
If you have files that absolutely must deleted permanently and with no chance of recovery after-the-fact, destruction of the storage media is an option. There are companies that offer the option of degaussing your mechanical drive, which will demagnetize the platter and remove its capability to store data. You also have the option to break the device apart with a hammer or other large and heavy object.
Destroying your drive will normally be a waste of hardware, as most permanent deletion options talked about so far will do the job of protecting important files and data.