Without an account
Your details in other people's address books
Someone who knows you may use Datta, and their address book probably holds your number or your email. Prove that one of them is yours and you can see how present it is, stop it being processed, or have it deleted. No account, no sign up.
The honest limit
If someone uninstalls Datta or revokes permissions, we delete what is ours and stop propagating, but we cannot reach inside their phone to remove what their operating system already had.