This website uses Google Analytics to collect usage information for the purpose of seeing what content is most viewed and which regions users are from.
Specific games such as Destiny offer extra functionality if the user opts-in to authorize the website with Bungie.net. This data is stored locally and never shared.
Removal of locally stored user data can be done either by using the sign out drop down for a given section or via the Settings page. If you are having any troubles, feel free to contact me at email@example.com and I will help sort out any concerns.