The +1 button is one of the distinctive features of Google+ that allows people to recommend contents. However, Google can use your +1 activity (also your G+ profile and social connection) to personalize non-Google sites. That is, the +1 personalization on non-Google sites lets Google to modify content and ads to you across the web. This option is enabled by default, but if you don’t like, you can simply disable it from your Google+ settings.
To disable +1 personalization on non-Google sites, login to your Google Plus account, and select Google+ settings from the Option menu.
Scroll down and click on “Edit’ option shown against ‘+1 on non-Google sites’ under Google +1 ( see screenshot above).
It will open a new page titled’ + 1 Personalization on non-Google sites’. Choose Disable option and click Save button the save your settings.