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From iOS 6.1 onward, users can now reset the Advertising Identifier on any iPhone, iPad, or iPod touch. This means you can basically throw all the anonymously gathered data about a device that is used to serve relevant ads out the window and start fresh, thereby removing any of the targeted data that has been accumulated and assigned to that Advertising ID.
Open “Settings” then choose “General” followed by “About”
Scroll all the way down and locate “Advertising”, from there tap on “Reset Advertising Identifier” and confirm the ID reset
Once confirmed, iOS will regenerate a new random blank ID.
You can also go the extra mile and turn iOS ad tracking off completely while you’re at that settings screen, which functions like a “Do Not Track” feature and prevents any of anonymous data accumulation from happening. What that will do is completely deny the ability for anonymous data to be gathered about the device to serve more relevant ads, outside of web cookies. For example if you have every Angry Birds app installed on the device and do 100 web searches for Angry Birds a day, disabling ad tracking would prevent you from seeing ads relevant to that topic.
Reasons why you might want to reset the Advertising Identifier
Keeping in mind that all of the accumulated data is anonymous, there isn’t some universally important reason to reset the Ad ID and by no means should it be considered standard procedure. Because the data is anonymized, the reasons to reset the ID tend to be fairly unique situations:
The ads you are being served are tied to past activities that are no longer relevant to your interests
You or your employer are particularly sensitive about privacy
Your iOS device is company owned, and you don’t want IT to (potentially) discover that you’re searching the web for things unrelated to work by having ads for unrelated stuff show up on the device
You are transferring an iOS device to a new owner or family member, and you don’t want to go all out and reset to factory settings for some reason
Of course there are other reasons as well, but again it’s important to stress this isn’t some super important thing to think about for 99.5{813a954d5e225a1509f22204ece89c855080ce25555f20805f61bed63cbfde3b} of iOS users.
For some historical background, the Advertising Identifier is a relatively new creation, and previously advertisers tracked anonymous data by the actual device UDID. Because the UDID is tied to hardware and not possible to reset, Apple created the Advertising ID as an alternative to the UDID, one which can be freely reset and directly controlled by the user much like cookies and browser history can be managed at any time.
