sgunhouse, sorry, I can't understand which folders do you mean. But thank you for answer anyway!
In my case I'm interested in deleting openned tabs information from Opera Sync server for the specific old device. Do you suggest booting this old device up, then closing all openned tabs in Opera Mini and then deactivating sync in device's settings?

I ask because I tried to close some tabs on this device but they didn't disappear from Opera Sync page (I tried to reload this page on pc several minutes after, closed tabs were still shown).

Is it possible now? Is it possible to delete synced data using device?

If that was so impossibly hard just to migrate old bookmarks to new sync system? Or at least make downloadable zip-archive containing html page with all opera link bookmarks?

[deleted]

>> Or everything has already been deleted?

> Most probably.

I can't believe this.
If that is true, Opera team has acted as a hipster irresponsible startup again... There was many important data at my opera link account.