If you want a clean install to work with (which is may be easier to work with than editing / deleting content) do the following:
Go here and DL the latest Rocket Launcher version:
code.google.com/p/gantry-framewo
... loads/list
Do a clean install and do not install the Sample Data. The Sample Data in this RL version is the Joomla core Sample Data and will not corrupt the install if not installed as it does not contain any RT components. So you will not wind up with any empty RT component / module / plugin folders to deal with later.
Go to the download section for your template and download the standalone version and the extensions for your template.
Install them as you would any other extensions.
Alternately, you can do a stock install of Joomla from joomla.org without the Sample Data, but you will have to go through one extra step of installing the Gantry framework (from the link above) or use the bundle package from template’s download section, along with installing the extensions.