I understand that you want to close your Microsoft account.
Before doing this, I would recommend going through the pre-check list, making sure to back up any data that you want to preserve, and removing all associated users and subscriptions. When you close your account with Microsoft, all information related to your account is deleted. This information includes subscriptions, licenses, payment methods, emails in Outlook, files in Onedrive, users, and user data.
To close the account, you can follow the instructions for How to close your Microsoft account:
1) Go to Close your account and follow the instructions to sign in.
2) Check that the page shows the Microsoft account you want to close, then click Next.
3) Read the list, and click the checkboxes to acknowledge you’ve read each item.
4) In the Select a reason drop-down list, choose the reason you're closing the account.
5) Click Mark account for closure.