You can directly Lock and Unlock your items from within your inventory. Click on "Lock" to begin.
In the Lock Items window, place the item(s) to lock an available item slot. Up to 18 items can be locked at a time. Once items are placed, click on the "Lock" button to lock the items.
There will be a final confirmation window that lists what restrictions are placed on an item when it is locked.
When locked, an item will display a yellow lock icon.
Should you later decide that you want to sell, trade, or dismantle the item, you will need to Unlock it. This can be done from the same Lock window by clicking on the "Unlock" button.
There will again be a confirmation window. It takes 72 hours to unlock an item.
The item will then display a red unlock icon to show that it is in the progress of being unlocked. Viewing the item information will display the remaining time to unlock the item.