1. If it does not exist, create robots.txt file in the root directory of the website.

2. Add these lines (as an example):

user-agent: *
Disallow: /wp-admin/
Disallow: /wp-includes/
Disallow: /wp-content/uploads/

Explanation:

user-agent: * – the asterisk includes every bot, not just search engine indexing spiders

Disallow: – followed by the path to the directory. The trailing slash can be replaced with its equivalent: /*  – but just the trailing slash is enough. It includes every file and sub-directory inside the directory.