By default Windows 7 offers top-right window a search field that allows you to search your files and folders.
Be aware that Windows 7 keeps a history of keywords typed during your previous searches.
To disable this history, it’s that simple.
Make Start and type “regedit” then press enter.
Then locate the key
HKEY_CURRENT_USER \ Software \ Policies \ Microsoft \ Windows
Then in the top menu use Edit => New => Key and name “Explorer.” Left-click to select it.
Then in the top menu use Edit => New => DWORD 32-bit and name it “DisableSearchBoxSuggestions”.
Double click on it and then enter 1 in the Value Data field and click OK.
Close the Registry and reboot for the changes to take effect.
For added security, backup system (System Restore) before writing to the registry.