How can I remove an extra element by selecting multiple elements?

Question

Adobe Illustrator

I have such an element now

. How can I make it like this, removing the excess, which is in the first photo.

I have already pressed all the buttons on this panel, nothing comes out.

I seem to be doing the right thing, I selected all the elements and clicked on the button on the panels, in the picture above
PS I'm just just starting to learn illustrator)))

Answer 1

https://www.youtube.com/watch?v=izi0mtItHh4