To delete the history of files that you opened in a common dialog box, use the Registry Editor to navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\ComDlg32.
To delete all the history, delete the LastVisitedMRU and OpenSaveMRU sub-keys.
To delete only the list of folders visited, delete the LastVisitedMRU sub-key.
The OpenSaveMRU\* sub-key contains a list of files, regardless of extension, that you opened.
The OpenSaveMRU\<Extension> sub-key contains a list of files with the <Extension> that you opened. To delete the history of .txt files only, delete the OpenSaveMRU\txt sub-key.
To delete all the history using a CMD:
1. Copy /Paste the following to a ComDlg.reg file:
2. Run regedit /s ComDlg.reg