You can remove your files from the Lockbook server by deleting them locally and syncing your changes.
To delete your Lockbook account, go to the Settings page of the app on any platform and select the Delete Account option. This action will permanently erase all data* associated with your account from the Lockbook server.
* Please note that server logs containing your username will not be deleted. Your username will also be reserved and cannot be reused for new accounts.