demilitarization

Short definition from Wiktionary

Noun

1. 1
   The reduction of the armed forces of a state or other political entity in its entire territory, usually at the end of hostilities or as part of a treaty.
2. 2
   The elimination of the armed forces of a state or other political entity from a specific area in its territory, usually at the end of hostilities or as part of a treaty, such as in the case of demilitarized zones.
3. 3
   The conversion of a military or paramilitary force into a civilian one.