Dismantling is the process of breaking down armor, weapons, and relic shards into feedstock, which is needed to enchant gear. The tier of feedstock received is equal to that of the item that was dismantled. The amount of feedstock derived is based on the rarity and enchantment level of the dismantled item.
Note: As of later changes current gear cannot be dismantled. Although enchanting materials can be dismantled, which produces Metamorphic Emblems or Supreme Metal, depending on material. Also fish can be "dismantled" for Fish Filets.
DISMANTLING CAN NOT BE UNDONE.
To dismantle an item, open the character's inventory window, and selecting the lowest center icon (above the space for the amount of currency), then selecting the item that is able to be dismantled. A confirmation box will come up and list the cost of the dismantling. Once you accept the fee, the item will be removed from your inventory and replaced with the appropriate amount and tier of feedstock.
Prior to the TERA: Fate of Arun, extraction was the way that items were broken down into their component parts. There were four extraction skills: Alchemy, Cloth, Leather, and Metal. Scrolls, with the required level and variety, were required to advance a character's extraction skills. The items were broken down into crafting materials instead of feedstock.