Go to https://www.linkedin.com/feed/following/ and scroll to the bottom of the page so all the people you are following have loaded in. Paste the following code into the browser console. Make sure to update your keywords that you want to unfollow people by.

linkedin.js

let people = document.querySelectorAll('.follows-recommendation-card');
let keywords = ['recruiter', 'recruitment', 'hunter', 'headhunter', 'acquisition', 'talent'];
people.forEach(person => {
    if(person.querySelector('.follows-recommendation-card__headline')){
        let headline = person.querySelector('.follows-recommendation-card__headline').innerText.toLowerCase();
        let shouldUnfollow = false;
        keywords.forEach(keyword => {
            if(headline.includes(keyword)){
                shouldUnfollow = true;
            }
        })
        if(shouldUnfollow){
            person.querySelector('.follows-recommendation-card__follow-btn').click();
        }
    }
});