Edit > Restore > Figure will reset it to its default state. This is not always a fully zero state.

Many figures come with a "zero pose" pose. If yours does not you may want to spend a moment manually zeroing everything then saving such a pose. Ensure that the option to save morph data is included.

Wardrobe Wizard does indeed include a zero pose button but I think you'll find that it will also zero out the magnets which you may not want. That being the case you may want to use it to create your zero pose then when saving to the pose library just omit the magnet data when you click the "save subset" button.

The Poser Pocket Knife has a selection of zero posing tools ranging from zeroing everything to just zeroing the morphs.

Hope that helps :)