See the Google Analytics Opt-out Browser Add-on to prevent data being used by Google Analytics.
Google Analytics places the following cookies, data according to gtag.js and analytics.js - cookie usage.
|Cookie Name||Expiration Time||Description|
|_ga||2 years||Used to distinguish users.|
|_gid||24 hours||Used to distinguish users.|
|_gat||1 minute||Used to throttle request rate. If Google Analytics is deployed via Google Tag Manager, this cookie will be named _dc_gtm_