How to disable personalized ads in Google AdSense
With Personalized ads (formerly known as interest-based advertising), Google AdSense by default serve ads based on your visitor's browsing history that Google tracks via its various tracking methods. Depending on your website's niche, disabling it can serve more relevant ads to your visitors and increase your AdSense earnings.
A niche with high competition in Google AdWords (where many advertisers bid for keywords in your site) would benefit from disabling the option. In contrast, sites with less targeted keywords might suffer.
Steps to disable personalized ads in Google AdSense:
Log in to your Adsense account.
From the sidebar, click on Allow & block ads.
Go to All my sites.
Click on the Ad serving tab.
Toggle User-based ads off from the Personalized ads section.