How do I remove my phone number from account? I did not have any phone number for about 4 months last year. I want remove my phone number for good for my entire account

Its very expensive to have a cell service, unless its under $20 year Im considering getting rid of my phone for good seeing the internet has so many other great free phone options. Therefore, I want to remove perminately from my account. Also, its not a good way of verifying me espically when I do decide to cancel my cell service for years.