Supposedly you can disable the "Steam Cloud."
Check
***this page*** under where it says "How Can I enable or disable The Steam Cloud?"
Individual games:
From the Steam Library, right click on any game and select Properties.
Under the Update tab, the Cloud Synchronization setting can be toggled.
All games:
From the Steam client Settings window, navigate to the Cloud tab.
Cloud can be enabled or disabled using the toggle next to Enable Steam Cloud Sync.
So if you're not able to delete saves from the "Steam Cloud" you may at least be able to prevent the game from using the saves in the "Steam Cloud" and to use local saves instead.
Sometimes I think the people who set these things up never actually play games themselves, or at least never replay them.
acebook
witter
