Magnetic tapes and other magnetic data storage media can be effectively destroyed either by destroying the data on the tapes or by destroying the tapes themselves. Without proper destruction, data is still recoverable by people not authorized to access it.
Data on magnetic tapes can be effectively destroyed by degaussing or overwriting. In degaussing, an alternate magnetic field is applied to the data, resulting in erasure of the data. In overwriting, each area of the magnetic tape is overwritten many times with alternate data and patterns.
Magnetic tapes can also be physically destroyed so that data is unrecoverable by shredding, in which the tape itself is torn to small bits, or by smelting, in which the tape is subjected to high temperatures so that it either loses its magnetism or physically melts.