In /home/user/.gpe/ the is
calendar
categories
todo

No config file.

There is /home/user/.gpe-calendar that you might want to delete.

There's also /home/user/.gpe-calendar-rendezvous though I don't know what kind of file this is.

I just know when you uninstall something, the config file is usually not deleted so for everything to reset back to normal, you need to find it and delete it manually.