Hey Jann,
What exactly do you want to get rid of?
Just by looking at your screenshot, I’d say, it’s probably best to just get rid of the whole model and start over; it looks like there is quite a lot wrong with your ‘Cube’…
If you want, you can upload your .blend file to Googledrive, Dropbox, or so and post a link here, then we can have a look.
