Degaussing (demagnetization) is a process for the safe elimination of the information contained in the hard disks and various media, based on exposing the memories to a strong magnetic field in order to eliminate the data and make the memory unusable, thus preserving the information stored in it from possible recoveries.

Degausser is a device that degausses hard drives, magnetic tapes, etc.
Note! For the data to be effectively removed, the electromagnetic field emitted by the device should be much higher than the magnetic coercivity of the carrier.
The National Security Agency has identified degaussing process (demagnetization) as an effective way to remove data from magnetic media.
Despite the fact that degaussing is a sufficient method of removing data from storage media, many companies decide to use a two-step process for destroying information: degaussing + physical destruction of media.