if you want to unistall a skin pack run unistaller from here: Control Panel\Programs\Programs and Features
1.in this part you can choice parts for unistall if you check all box and click on unistall button skin pack will be removed from your windows.
note: if you want to remove all files and backup check the last box but its better to uncheck this box to have a backup files.
2. in this part unistaller ask you about remove all files and backup if you want to remove it then click in yes button.
3. after complete unistalling click on next button.
4. now click in finish button your system will be restart to restore back your windows files.
after restart if you see your system not started its problem with your antivirus so run safe mode and run unistaller again.
after restart if you see your boot screen not back to normal then use this tools
after boot if you see your login screen not back to normal then use this tools
After login if you see your icons not back to normal you need to refresh icon cache form here
Note: after run refresh icon your explorer will be closed and you need to logoff your windows with Alt+Ctrl+Delete Buttons.
if you cant back to normal mode after refresh icon cache your system files not restored so use this tools
Note: after 100% complete your system will be restarted to restore files if its not complete to 100% your windows resource have problem so you need to restore your files by your self with this tools:
1. Windows7 StartOrb Changer
with Windows7 StartOrb Changer you can restore your start button.
2. Windows7 TrayIcons Changer
with Windows7 TrayIcons Changer you can restore your system try icons.(network,sound,battery,action center)
3. Windows7 NavigationButtons Customizer
with Windows7 NavigationButtons Customizer you can restore your explorer buttons.
4. Windows7 Source Patcher
with Windows7 Source Patcher you can restore other parts of windows.
5. after all this way if you cant back to orginal windows use this tools:
windows 7 x64
windows 7 x86
windows 8 x64
windows 8 x86
Note1: its better to disable antivirus when you running unistaller or installer.
Note2: if you cant login in your windows after install or uninstall skin pack just run System Restore from boot option.
you can watch video about how to install and unistall a skin pack here