Back in September, Apple officially announced its acquisition of Shazam, the popular service that is able to quickly recognise songs by listening to small snippets.
The same page also presents users with the option to thoroughly delete all of their stored Shazam data, including but not limited to user IDs and Facebook login credentials. Tagged music will continue to be stored locally. It will, however, no longer sync across devices and will be permanently lost upon uninstalling the app.
Analytic logs - i.e. information on how users handle the app - won't be erased in this process, but they will no longer be identifiable to a user. Consequently, those who will use the app without having signed into any account in it can continue doing so anonymously; Shazam's data will not be identifiable to them in any way.
Image via MacRumors