That’s not pagination, Discourse doesn’t have that. That’s just a navigation control that tells you you are at Post #1 of 2 (in your example). Clicking it brings up a slider to move to a different part of the Topic.
Inspect the page in mobile view on desktop and remove it with some CSS if you like.
But this is a useful button, especially on longer Topics, so you should probably not hide as it will make it harder for your users to navigate.