Follow the given steps for configuration to clear recently opened
documents automatically:
To edit the computer registry, first you should log onto your
computer with administrative rights.
Click Start button and type regedit in Run
option then press Enter for next.

Navigate to HKEY_Current_User \ SOFTWARE \
Microsoft \ Windows \ CurrentVersion \Policies\Explorer

Now in right side panel, click right to create a new
DWORD value with the name ClearRecentDocsOnExit and then set its value
to 1.

But next time, if you want to disable this functionality then
simply change the value of data box to 0 or delete the
ClearRecentDocsOnExit
DWORD item.
Now
close the registry editor and restart your computer after any changes to
go into effect.