Replacing #’s on acct w/iphones

Hi, my husband broke my iPhone 11pro, so I went and got another iphone(12), I still owed money for the 11 and had to add another line on the account.  Since that time and now, a company was able to repair the 11pro. My question is, my husband’s old phone died. I swapped the SIM cards on the 12(removed my sim, put his in it), I went back to my newly repaired 11pro. Since the extra line is no longer needed, shouldn’t I be able to disconnect it? Quick note, all the SIM card flopping has Caucasus our account on line to look like we now have 2 11pro’s....another issue apparently.  We are keeping both phones that need paid for; iPhone 11Pro, iPhone 12.