Hide This Part (hide-this-part) free WordPress plugin

Hide parts of the content of your posts or pages by surrounding it with [hide-this-part] and [/hide-this-part] shortcode. You can even set the text of the more link (that will make hidden parts visible) by passing the parameter “morelink” like this: [hide-this-part morelink=”show the rest”]. In this case the text of the more link would be “show the rest”.
See also the official plugin documentation.