I have got home early, so checking ccleaner, i have ver 3.28.1913 which is latest.
As a first run, I would restore defaults (the option is in Options, Advanced) then click Run Cleaner. It will take a while.
Then go to Options, Settings, and where it says Secure Deletion select "secure file deletion (slower)" and select Complex Overwrite (7 passes).
Click on the sweeper icon (Cleaner) and under the Windows tab find Internet Explorer And put a tick next to Autocomplete Form History and a tick next to Saved Passwords.
Under Windows Explorer, put a tick next to Network Passwords.
Keep rest as they are.
Then click on Applications tab.
If you have Google Chrome, put a tick next to Saved Form Information, Saved Passwords, Compact Databases.
Then click Run Cleaner. It may take a while. Or it might not, depends how much stuff it finds.
Then do a simple clean of Registry by clicking the Registry icon, leaving everything as it is and click Scan For Issues. Once that is done, click Fix Selected Issues. It will prompt to backup, select No. Then a box appears, select Fix All Selected Issues. It will probably do it very fast. That will have cleaned the registry of redundant stuff.
Now if you have deleted all your work documents and feel that you need it such that they can not be recovered, then you need to Wipe Free Space (with the currently selected 7 pass option).
So click the sweep icon (Cleaner) make sure the Windows tab is selected and scroll down the list to the bottom. Tick the Wipe Free Space box and a prompt will appear warning you that it will take a significant amount of time. click OK.
Click Run Cleaner... go to bed. When you wake in the morning it may have finished, it will take many hours.
Hope that helps.