How can i delete one of my organizations?
you can refer : https://community.apigee.com/articles/1618/organization-and-environment-deletion-in-apigee-on.html
But before deleting organization, you have to delete all proxies, kvms, environment etc.
Are you speaking of Apigee Edge? Apigee X? hybrid? The process is different depending on what you're using.
the account is a apigee edge account, so not a on-prem enviorment but a cloud only enviorment.
Then you can take help of Apigee support.