Disable Pages

Are you using custom menus? Using a custom menu allows you to precisely control what appears in your menus.

It’s probably not possible to do this (at least I’ve never heard of anyone trying this, as pages are essential to all the WP sites I’ve seen). If you tell us why you need to do this, we can probably provide a solution to your actual problem.

If I gather what you are trying to do, ie, make the post not visible on the front end either in a menu, or if someone visits it directly, but still have it in the wordpress admin, just change the post status to draft.

No, I wanted to completely disable the post type “page”. I don’t want to have any options to create or edit pages in the admin menu nor in the front-end of the wordpress blog.
So no pages just posts.

Okay…but why? Why not just not use them?

I just don’t need them.
But Ok, I’m going to ignore them ??

If you want to prevent other users from creating pages, there are ways to do that. Is that what you need?

So if it’s not possible to disable pages then I will edit the user capabilities.

There are many plugins for that. I recommend the User Roles Editor.

could you please point to a free plugin which disable pages across a multisite?

As mentioned, use any of the role editing plugins to remove all page related capabilities from all roles. All plugins listed in https://www.ads-software.com/plugins/ are free.

Next time please start you own topic, more people will see your question and it’s the preferred practice here.