For a Joomla! newby the guided tours & sample data are a valuable first introduction to the ecosystem.

After that, the  extensions just add to the load on your website.

Unfortunately, you can not remove the guided tours completely from your system. They are part of the Joomla! Core package. And future updates will fail if you do so. But you can hide and deactivate them.

Steps:

• Unpublish the administrator module for the Guided tours.
• As this still injects css scripts in your administrator, you will need to unpublish the guided tours system plugin on the Extensions: Manage page.
• As you are already that page unpublish the Component en Module as well.
• In your database, you could truncate the tables guidedtours and guidedtour_steps, to save a bit of space. Do not remove them.

The above steps are performed by the extension in the download below.