iphone esim and phone question

I have a new iphone 15. My old Iphone 12 transferred over smoothly. The Esim transferred over.

Everything is working properly on the new iphone 15 with a complete transfer from the old iphone.

I wiped my old iphone and signed out of everything. I read that I was supposed to delete the esim on the old iphone if it was transferred successfully on the new iphone ...so I went back into the old phone and did a quick set up with no apple id log in etc with my new phone turned off. As soon as the old phone booted up I could see the bars for cellular service at the top...I went into settings-cellular and there was no where to click delete esim. So I must have deleted it when I did a complete reset and erase on the old phone. I went into the "phone" app on the old phone and my cell phone number was still there. I tried calling from that old phone and it would not work (which is good); I turned off wifi and even though there were cell bars--it did not work ...(which is good and means there is no cell service)

My questions are:

1. if the esim is gone on the old phone--why are there still cell bars showing at the top?
2. If the Esim is gone on the old phone--why does my cell number still show up in the "phone" app?

I want to get rid of the old phone--but don't want anyone to see my phone number under the "phone" app.

In the old days- I just took out the SIM card.

Thanks