WordPress allows you to create child pages, Child Pages are those pages that are created keeping some page as their parent so that their content and category falls with in them. This makes page management easy and more useful. But sometimes you might not want to allow your users to create child pages of some particular pages created by you. For example: If you don’t want your users to create child pages for your About and Contact pages etc.
By default WordPress doesn’t provides you any feature to enable restriction on keeping any page as parent. But you can do so by using new WordPress plugin called Restrict Page Parents. The plugin allows you to restrict page parent options on those pages which are owned by the user, with the option of forcing a page parent.Hence user only sees those pages owned by him not by other users in page parent meta box. Also it can force your users to select a parent page before publishing or saving the pages created by them.
Simply install and activate it then visit your admin area Dashboard -> Settings -> Page Parent Restriction and the options as per your need. It can also prevents editor users from adding their pages under sections of the WordPress website even if they do not own or manage. Editors can be confined to their own section of the website making yours website more secure. Other than this you can also set permissions for each user role or specify them on a user-by-user basis.