Hide Users Contact Details?

Hi,

I am wondering if there is any codes or plugin that will make it possible to hide certain text from users?

What I want: When my users post an ad, I don’t want their contact details (email, phone number) to be visible.
As I can’t “stop” them from writing what they want, I want this to be automatically hidden. I remember seeing this on certain classifieds websites I’ve used before.

Does anyone have any ideas or comments around this?

Thanks guys