Some browsers (at least Chrome and Firefox) supports a header called Clear-Site-Data [0]. When sent, this header tells to the browser to delete information like caches, cookies, local storage...
This is interesting for at least two reasons:
* it makes sure that everything that could possibly be done to preserve user's privacy is done
* it can helps mitigate security issues where malicious users has successfully injected code by making it harder to persist the attack





[0] https://w3c.github.io/webappsec-clear-site-data/