ALT + F4 is a very simple way to close'em totally but it is ok to simply slide them down like on W8. When pulled down, they don't use any resources
As mentioned several times. Over the past couple of days, ppl are continually starting new threads when these things could easily be posted in existing threads where exactly the same thing is under discussion. Just requires some reading (only a bit) of the forum. This thread.
I think that the ideal is to close one by one. Maybe this tweak to speed up applications you interested. Code: Windows Registry Editor Version 5.00 [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Serialize] "StartupDelayInMSec"=dword:00000000
It may be better to remove them from the start screen, so you won't hit them accidentally when trying to start a desktop application. If it's not running, you don't need to close it.