I have been trying to delete the premium feature for a few days now and it does not appear to work.
Can you please clarify if you're trying to delete your personal Todoist account or just want to cancel your Todoist for Business account?
If you're trying to cancel your Business account, you will need to enter a new password as you can't use your Google password for this. To do this, just follow these steps:
1. Click on the gear icon
2. Go to Todoist Setting
3. Go to the "Accounts" tab
4. Click on EDIT beside the password section
5. Type in a new password
You can then use this new password to cancel your Todoist for Business account. If you have additional questions, feel free to ask.