Need to delete modem

Hello I have 2 modems detected on my account , the one I am

currently using (both are my own personal equipment) is not being recognized because I still have older speeds (I upgraded my plan as well to 1gig up and down). And also when I look of my device it shows I have the old modem as my device even tho it’s unplugged and I changed it and activated a new one . Need help with deleting my old modem so that this new one is recognized.