How can I remove a trusted number from my Apple Account?

I can login to my account with no issue on all my devices and via my laptop but I am unable to see an option to remove a trusted number assigned in the account, I still own this number so I'm not to concerned but I will be closing the service soon, it's also no longer in an apple device and I'd like to tidy my account up.

Do I have to put the sim back in an apple device to be able to remove it from my account? or something else? Thanks in advance for any help, as all current searchs have led no where useful.

[Re-Titled by Moderator]