You must UNcheck them.
But try this.
Type Gpedit.msc in the RUN box.
Open User configuration - Start Menu and taskbar.
Scroll down and enable these two items
Do not keep History of recently opened documents.
Remove Recent Items menu from Start menu
To perform the taskk, double click each item above and "enable>"
This does the same as unticking the previous two boxes, but might work for you.