The method is as follows:
1. Use Win+R key to open the run dialog box, and enter gpredit.msc command in the run dialog box to run the Group Policy Editor;
2. Under Group Policy, expand User Configuration-Management Template-Taskbar and Start Menu in turn;
3. Find the items "Do not keep the history of recently opened documents" and "Clear the record of recently typed documents when exiting" in the right pane;
4. Just set it to "Enable".
Through the simple operation under the above group policy of win7 system, users of win7 system can be helped to close the document opening record on the system reserved taskbar. Interested users may wish to learn.