When you right click on the icon packs?
"Remove" shows up on right click in the normal DX environment (not the build environment) when you right click on a DX object. If you go into the DX build environment you can right click on objects and get the properties menu.
As for using iconpack icons for other things, look in this thread: https://www.wincustomize.com/Forums.aspx?ForumID=19&AID=70120#541157