XAMPP is a package. You can't just take Apache, PHP and the other stuff without MySQL.
But thats okay. XAMPP itself doesn't need any installation (the installation is nothing more then unzipping and setup for the modules and paths). XAMPP don't need any Windows PATH Variables or Registry entrys.
So, you can simply "install" XAMPP as package and just start the components you need.
If you don't need mysql, just don't start it