The RocketLauncher should never be used unless the sample data is installed. The whole point of the RocketLauncher is to give users a way to get up and running quickly by replicating the demo. All of this is accomplished with the use of the database information in the sample data sql.
Without installing sample data, the RocketLauncher is not only the same as a default joomla install with no sample data, but it will actually be badly broken as the launcher contains all of the files and directories for the extensions used in the demo, but none of the database information will be present.
This means that if a user installs the RocketLauncher, but does not install the sample data, most of the extensions will not work as they won’t be detected by joomla, and attempting to install them will cause errors and fail because while Joomla doesn't see them, the directories and files are there.
Basically, there is nothing to gain by using the RocketLauncher without the sample data, and it will cause a whole lot of issues down the road.
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
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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.