Hi,
The ability to toggle off autosave is not available in Office Online as yet since the idea is to ensure users do not lose their work by accidently closing their browsers or hitting the back button.
That is not to say it is definitely not something we will ever do, but with the two workarounds I provided above most changes can be reverted.
There is however, user request we are getting for a manual save. Please review and vote at the following link:
http://word.uservoice.com/forums/271331-word-online/suggestions/9210012-save-online-documets-when-requested-not-after-eve
We are constantly going through user requests to prioritize features for our online products.
For any other request or to view what other users are requesting visit us at:
http://word.uservoice.com/forums/271331-word-online
Poonam