How can I delete files inside the trash folder I have not sufficient access rights for? It shouldn't be important for my question, but I'm using Gnome and can't delete in nautilus and don't know where the trash is located in the cmd. I'm using my ordinary Ubuntu-account.
I have no idea about how you managed to get those folders in your user's trash folder without moving them there on purpose, however: your user's trash folder is located in
You may manually empty the trash just by removing the whole folder (it will be recreated when a new file / folder is moved to the trash):
sudo rm -rf ~/.local/share/Trash