Moving users from one account to another with the same email address.

Hello,

My nonprofit organization, recently got a subscription for Microsoft 365 Business Premium. We are currently working on migrating our emails, contacts, and data form Google Workspace to Microsoft 365. A few of our employees have Microsoft accounts with the organization email. After migrating to Microsoft 365 and connecting the domain, we would use the same emails to assign them as users in Microsoft 365 Business Premium. Would I need to delete the current Microsoft 365 accounts for these employees before moving them to Business Premium? Or since they already have a Microsoft account with that email do I only need to make sure their license for Microsoft 365 is removed and the Business Premium licenses is added?