When uninstalling, dpkg takes package names, not filesnames. Also, it's better to use apt-get when possible as unlik dpkg, it also takes care of package dependencies. If you want to remove just the kernel, use the following. This command will automatically uninstall ramzswap-dt (and probably dt-init-scripts).

Uninstalling the other packages -- or actually reverting to old versions -- isn't trivial but certainly doable. However, it's not neccessarily recommended. :-)