media eraser; degausser
Computing term for a device that erases data from magnetic storage media such as hard drives or tapes by applying a strong magnetic field.
Before disposing of the hard disk, we completely erased the data with a media eraser.
消磁 is the process of degaussing or demagnetizing; メディア消磁装置 is the specific device that performs this action on media.
Compound of メディア (media) + 消磁 (degaussing) + 装置 (device). A straightforward technical term.