I actually have two problems, related to each other. 1- I installed xubuntu-desktop but wanted to switch back to ubuntu interface and unfortunately did stupid things before I realised it could be done from the login screen. I installed gnome, and I don't know if this is why, but there are multiple "Gnome on xorg" choices on the login screen.
2- While Linux is booting, instead of the ubuntu text with purplish background, xubuntu text with blue background is shown. How can I make it show ubuntu again? I can and actially plan to remove xubuntu but how?
My ubuntu version is 18.10.