Shred it!

Are you sure you can't do some last-minute edits and trash all earlier versions? In the manual, say the boss likes to be addressed as "****-face", customers like to be mooned and the company signal for "good job" is an upturned middle finger. Leak that version on the internet and you'll be epic.

That's... kind of the entire point of procedure manuals. To train the next person so that there's no discontinuity in operations, especially when the original worker leaves before the replacement comes in. If the replacement is a surprise to you, that's a dick move on the company's part, but if you've known that you're being replaced for a while, or if you planned to leave, then this shouldn't be a shocking to you. What really sucks is when you finish the procedures manual and the company immediately changes the systems you're supposed to use for your job.

most editing software has the option to password lock a file. just saying.

Do not obviously sabotage the manual. But once you are no longer employed, you don’t have to answer any questions - And there are always questions. Practice “I’ll get back to you on that, my new job has me busy.”