You can manually hide them by going to Start> Setttings> Taskbar and Start menu> make sure the "hide inactive icons" box is ticked and then go into "customize." That will pop up a list of your icons currently in the system tray. click on one to highlight it and a little pull-down menu will show up to the right of it. Select "Always hide" for the ones you want to hide. It acts the same as hiding inactive icons, just a little more control over what you want to hide is all.