The Undo command in Word 2016 undoes anything you do in Word, which includes formatting text, moving blocks, typing and deleting text — the whole enchilada. You have two handy ways to unleash the Undo command:
Press Ctrl+Z.
Click the Undo command button on the Quick Access toolbar.
You also can use the Ctrl+Z key combination, but an advantage of the Undo command button is that it sports a drop-down menu that helps you review the past several things you've done, which can be undone.
Regrettably, you cannot pick and choose from the Undo command button's drop-down menu; you can merely undo multiple instances of things all at one time.
The Undo command works sporadically sometimes. Before this happens, Word warns you. For example, you may see a message such as "There is not enough memory to undo this operation, Continue?" Proceed at your own peril.
The Undo command doesn't work when there's nothing to undo or if something simply cannot be undone. For example, you cannot undo a document save.