What this browser has stored
Everything below is held against this browser — and, where you are signed in, against your account. There is nothing to type in: both credentials travel in cookies your browser sends automatically, and neither is readable by scripts. Back to the privacy notice.
Nothing is stored for this browser. No id has been created, so there is nothing to show, download or delete. That is the normal state for someone who has only read pages with measurement off.
Take it with you
The same information as a file, in JSON.
What is not here
Two things, and neither is an omission. The count of pages served where measurement is off by default has no id in it at all, so it cannot be attributed to you or to anyone. And the forecast archive records what the weather models said about a place, which is the same whether or not you ever visited.
Backups are the honest exception: a nightly encrypted copy of the site's data is kept for up to a year, so deleting something here does not reach the copies already made. They age out on their own and are never used to bring anything back.
Delete it
“Forget this browser” on the privacy page clears the id, signs you out, and detaches anything held against the browser. An account — and the places and dates saved to it — is deleted separately, on the account page. Two credentials, two deletions, on purpose: forgetting a browser you borrowed should not be able to destroy the account you signed into on it.