There are some differences.
1. Work/school accounts with full Teams subscription, business/enterprise.
2. Personal accounts (Teams for personal use), limited features.
3. Teams free (Teams free organizations) including some business features.
When deleting a Teams free org. you don't delete your account but the organization. Once again, did you create a Teams free org. with teams and members in it? Then it's Teams free.
You don't delete a Teams for personal use account (also for free). You delete the associated Microsoft account.
So the question here is if you have used the same address for your Business Basic subscription which includes Teams as for the one you want to delete, whatever service you signed up for, and that will decide how to proceed. Also, important to use InPrivate windows as you might noticed.
If this still doesn't help go here for official support
https://docs.microsoft.com/en-us/microsoft-365/business-video/get-help-support?view=o365-worldwide