Read only - Custom End User Fields

Hello,

I have been reading posts that you can use custom roles to make user fields read only. I am not seeing this option although I am able to create custom roles. 

It also looks like you can hide these via API (https://support.zendesk.com/hc/en-us/community/posts/115009258647-Hide-end-user-fields) - is there a way to make them read only in this same way? 

Thanks!