Use this recipe to transfer FSMO roles between domain controllers.
When both the domain controller holding a FSMO role and the domain controller you intend to transfer the FSMO role to are both online, functioning and replicating perfectly, you can transfer FSMO roles without problems. If you can't transfer successfully you can seize the FSMO roles.
To transfer the Schema Master and/or Domain Naming Master FSMO roles, you'll need to be signed in with an account that is a member of the Enterprise Admins group. To transfer the other FSMO roles, you'll need to be signed in with an account that is a member of the Domain Admins group.