What is the best way to uninstall some default packages that I do not use?

[rokytnji]

Hit and miss depending on the size of package uninstall.

Synaptic will give a list of packages to be uninstalled like libraries. Before allowing you to proceed. In a new window popup. Under the "to be removed"  arrow. Something that can break other applications if removed if they depend on the same libraries. So one must be careful with large applications before proceeding.

If you do not know what you are doing and things are working OK. I'd leave well enough alone.
Anyways. you might want to mention what packages you are talking about. At least.