In WordPress CMS absent standard way to disable HTML auto formatting. But there is a way to turn off auto formatting with help an plugins. For this you can use any from next plugins: "Raw HTML", "Raw HTML Snippets", "ACE HTML Block", "WordPress HTML", etc. You can find they in official WordPress repository by search query like "raw HTML" and other similar. Select any most suitable for you, install, activate, read instructions and use it.
E.g., "Raw HTML" plugin lets you enter any HTML/JS/CSS code in your posts without changing by WordPpress, as well as disable automatic formatting on a per-post basis.
Usage: just wrap your raw code in [raw]…[/raw]
tags.
To avoid problems, only edit posts that contain raw code in HTML mode.