If you used your organization’s domain (@mycompany.com) to create a personal Google Account. And now your organization wants to use the domain for a managed Google Account. This creates conflicting accounts as you have the same address for your personal Google Account and your organization’s new managed Google Account.
Fix a conflicting account
The next time you sign into your personal Google Account (the original one, not the account your organization set up for you) you’ll be prompted to resolve the conflicting account. While you're resolving the conflict, your data remains safe and accessible.
Find out more about the different Types of Google Accounts.