Log into your Hiver admin panel at hiverhq.com, and then select “Account” from the top. In the dropdown menu that opens, select “Delete Hiver”. You’d then be able to delete Hiver from the next page.
Additionally, you should also remove the Hiver browser extension from your browser if you had that installed.
Do note that deleting your Hiver account does not delete any labels and emails from any Gmail accounts associated with Hiver. However your notes and templates stored with Hiver will be deleted.