What happens when you deactivate or delete Offloft

Deactivating Offloft stops background work and keeps all its data, and your site serves media from your server again. If some files exist only in the cloud, Offloft warns you first and offers to bring them back. Deleting the plugin never deletes files in your bucket or on your server.

Deactivating

Background work stops.
Your settings and file records are kept, so reactivating picks up where you left off.
Your media loads from your server.
If Pro removed local copies, the Plugins screen warns you and offers Bring back to server. Those files won't load from your server until they're back.

Deleting

Deleting the plugin keeps its data, unless you turned on Remove all Offloft data on uninstall in Settings → Advanced. With that on, it also deletes its settings, connection, file records, activity and scheduled tasks from your database.

Either way, your files stay in the bucket and on your server.

Removing everything cleanly

Run Bring everything back, so every file is on your server.
Deactivate, then delete the plugin.
Delete the bucket yourself in your provider's dashboard, if you no longer need it.