Can I Remove Non performing Keywords From My Website?

Hi everyone,

I have this website that I built about 7 years ago. Back then, I knew nothing about keyword research as much as I do now. So, I filled the website with keywords having 5 searches a month! (lol). But now, with my knowledge, I have since discovered that this was a huge mistake. I just want to know if removing these non performing keywords will affect my search engine rankings.

However, this is very important. This same website is now earning more than 5 euro per day on a good month. The irony is that out of about 70 keywords (didn't know anything back then), only less than 10 are bringing adsense clicks for me.

What will happen if I get rid of the rest 50+ keywords that are no longer being searched or not bringing visitors or are only bringing 5 visitors in 6 months plus? I plan to replace them with good keywords based on what I now know and successfully doing. But before going ahead, I just want to know how google will view this and what should I do about all these pages that are already indexed? What if a visitor to any of this page drop by once in a while?

Please, I need your suggestions. Leaving the site as it is not affecting my income but I just thought that replacing these keywords with good ones will earn me more money. What do you think?

Thanks everyone for taking the time to read and respond. I really appreciate it.