Clear Xfce4 session

This question is answered in Xfce wiki, subsection Some of my applications are always started when I login:

There are two possible reasons why the application is started: It is saved in the last session or it is listed in the auto started applications. Follow 1 of the two steps below to get rid of the applications.

• Start the xfce4-autostart-editor and remove the application(s). You can also manually delete those files in ~/Desktop/Autostart and ~/.config/autostart.

• Most of the time closing all the applications and save your session when you logout is sufficient. If this doesn't work, remove the content of the ~/.cache/sessions/ directory when you're not logged in. And if you don't want xfce remember every session you should turn off (uncheck) “Automatically save session on logout” in Settings Manager → Sessions and Startup (tab General)

Run this:

rm -fr ~/.cache/sessions/*

and Xfce should starts cleanly.

Also, you might need to clear the entire .cache directory if the above doesn't fix the issues:

rm -fr ~/.cache

Using the GUI seems to work as it should, at least in my version of Xfce (4.10).

In Xfce Menu go to 'Session and Startup'

And there, under Sesion/'Clear saved sessions':