By default GTA:SA settings, the unequip key will be Y on the keyboard. The name for this key inside the GTA:SA key configuration is: "Conversation - Yes"
The Unequip key has a variety of uses all dependent on what item you are holding.
- Small items
- The item will be put into your inventory.
- Small Weapons
- The item will be put into your inventory, if your inventory is full it will be holstered.
- Medium Weapons
- The item will be holstered.