Click on the dropdown menu on top left under Identity Plate and choose to pause the sync to stop it.
Thanks for the update.
Sorry, I assumed you were talking about sycing through Lightroom Desktop.
For mobile, you can go to auto add and turn off that option.
Didn't work :-( The "auto add" feature I think refers to adding a picture from the gallery to the app automaticaly.
I think the only way to stop the auto sync with the cloud is to not have the trial or membership and I don't know how to stop that.
Syncing would automatically stop when your trial period will be over.
Also, if you are using this device only on internet data pack, then you can probably turn on the option "Sync Only Over WiFi"
This is the very first time I ask my trial version to over :-S