Having problems with installation & uninstallation of some programs

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http://forums.fedoraforum.org – Hello people, I installed Skype on my Fedora 17 64-bit. The icon comes down bottom right. I can't see the icon in the applications. I knew I messed up something while installation. Hence I want to do it again. I tried uninstalling by yum remove skype. I keep getting this error. Code: yum remove skype Loaded plugins: langpacks, presto, refresh-packagekit No Match for argument: skype No Packages marked for removal And then I tried installing Libre Office. I got into the root with su - command. I used wget some link to download the thing. When I tried to extract, this is the error I go (HowTos)