Today, I tried to remove a "Home" phone number on PayPal, and it wouldn't let me, because the interface seemed to require I HAD to have at least TWO phone numbers to remove one. That makes sense, but this was a "Home" phone number, as in a landline, not a "Mobile" phone number. I'm removing the "Home" phone number because I don't use it anymore, I still have a "Mobile" phone number, and that should have been enough, but the interface didn't let me, because some programmer didn't consider that when you click to list your "Home" phone numbers that doesn't list ALL your phone numbers.
Fortunately, there is one way to fix this.
Call PayPal.
If you ask to talk to a human, the human can fix this sort of issue for you. At least one fixed it for me.
Observation
If you click on "Contact Us" on PayPal, it will take you to a page to search for help topics.
On this page, there is a button that reads "Message Us," but it shows an AI-powered chat bot instead of an actual human being, who is completely useless to solve issues like this. And trust me I have tried.
You need to call them.