The act of magnetically erasing all of the data on a disk is known as:

Wiping (or overwriting) replaces existing data with patterns of zeros, ones, or random data using software, but does not use magnetism and is a distinct sanitization method.

Dissolution refers to physically destroying media using chemical solvents to break it down, not a magnetic erasure process.

Scrubbing is a general term for data overwriting or cleaning processes performed in software, not a magnetic erasure technique.

Degaussing exposes magnetic storage media such as hard disk drives or magnetic tapes to an intense alternating magnetic field that randomizes the magnetic domains storing data, effectively destroying all recorded information. It is recognized by NIST as an approved sanitization method for magnetic media and renders the data unrecoverable by any known means. Degaussing typically also renders the media unusable, as it destroys the servo tracks needed for drive operation.