Can I add a bogo offer and close one of my original lines down the road?

so I originally signed up for 3rd line on us with insider discount. It coded the 3rd line as a bogo line (I see the bogo offer on both line 2 and line 3)

If I added a bogo line to my account could I close the original first line technically after a couple years without losing my free lines? I would still be paying for 2 paid lines for the first bogo offer and the 2nd bogo offer is stuck to the last two lines added so would this work?