How to remove or change the x-robots-tag header?

Question

WordPress

This is the standard url in wp site_address/wp-json/ :

Answer 1

If you look at your screenshot, it is not clear why you need to change /wp-json, because it should be in noindex.
If the question is in general, then this tag can be set at the level:
1. Wordpress SEO plugin
2. robots.txt
3. at the server level
Usually and quite often in robots.txt you can find such a directive (or very similar):
Disallow: */ wp-json/*
Then look at the expediency of the ban.