How to disable or clear list of recent files in Ubuntu Unity Dash? I can find many ways to do so in older version of Ubuntu but none of them work in 14.04.
In order to clear usage data from the dash you can open Security & Privacy:
Clear Usage Data and select the desired time frame:
You can also disable all monitoring of files from this configuration menu or deselect specific file-types on the left side.
The best cleaner I know for Ubuntu is Bleachbit install and execute with the following commands in a terminal:
sudo apt-get install bleachbit sudo bleachbit