Yes, you can edit or cancel an open indication at any time.
To edit an open indication
Go to your My indications page (https://notice.co/my/indications)
Click on the three dot menu (highlighted with pink box in screenshot below)
Select Edit
Update your indication and click "Finish" when complete
To cancel an open indication
Go to your My indications page (https://notice.co/my/indications)
Click on the three dot menu (highlighted with pink box in screenshot below)
Select Archive. Your indication will instantly be archived. You can unarchive at any time in the future if you wish