Lightroom Mobile - completely turn off sync

You can pause sync indefinitely, which is just the same as turning it off. I personally wouldn't do that, but we can all have different opinions. I keep all my synced images (16k) permanently downloaded as Smart Previews on my phone, so it wouldn't matter if I have no cellular or wifi connection, I can still edit as required. Smart Previews are perfectly adequate for most editing, but if I thought I'd likely need to do more detailed sharpening or brush work on some images I can always download the full resolution originals before heading off into the wilderness.

How do I pause sync indefinitely? The only options I see are to toggle "Use Cellular Data" (which is off) or to "Pause Sync" after it begins automatically syncing as soon as I get on wifi.

I should add that my long hikes a thru-hikes, 5 to 6 months away from home with no access to my desktop. I want to be able to handle all editing from my phone and then back them all up to my desktop when I get home.

Just tap on the cloud icon and then tap on Pause Syncing (you can do that at any time, even if there's no syncing activity). Then it'll stay paused until you tap on Resume Syncing.

Pause sync indefinitely is NOT the same as turning it off.