Unless I haven't found the hotkey, I haven't yet found a way to unequip my shield without going into inventory. I feel like this has a few drawbacks in gameplay:
1.) It just looks weird holding a block and shield at the same time
2.) If I'm not holding a sword, but am rather holding a block/torch/ho/etc while my shield is out, I can't actually use right-click to use the shield because i'll just place a torch or something. Or, vice-verse, i won't be able to place blocks bc i'll just keep shielding.