PURPOSE
The purpose of this policy is to provide guidelines for the appropriate disposal of information and the destruction of electronic media, which is defined as any storage device used to hold company information including, but not limited to, hard disks, magnetic tapes, compact discs, audio or videotapes, and removable storage devices such as USB flash drives and micro-SD cards.

From the policy:

ELECTRONIC DATA DISPOSAL REQUIREMENTS
Secure removal of files from computer systems
In the secure removal scenarios, the device is not being transferred or retired but merely shored up to ensure confidential data is removed. This operation involves “shredding” the electronic file and leaves the operating system or computer intact.

An example would include reading a confidential legal brief in the form of a Word document then erasing it via software that deletes the file then overwrites the space where it resides to prevent recovery.

In some cases, you can specifically shred a file, and in other cases, you can delete it and then run a tool to erase free space on the drive, meaning anything recently deleted will be permanently flushed from the media.