The Startup Manager gives you control over the programs that are automatically started by Windows.
The list on the left contains the programs that are set to run when your computer starts. Programs that have a blue checkmark to their left are set to start at the same time your computer starts, and programs with the empty circle are not.
To remove a program from startup just click the circle on its left to remove the blue checkmark. After being unchecked, the program will move to the bottom of the list, and its icon will turn grey, so you can tell it has been deactivated. To make it active again, you just have to make the checkmark reappear by clicking on the empty circle. If you wish to remove it from the list once and for all, hover over its name and then click on the red garbage bin button.