Hi, this is a public forum. It's recommended you don't publish personal info like phone numbers. You can edit your post to remove it.
You'll need to contact Optus directly to change anything about your account. I suggest live chat online.
Note Optus generally provide a landline for free on all plans. So you can leave it there for all incoming calls. If your paying extra reach month for a phone pack (unlimited national calls) then you just need to cancel this ad on.