Accounts are owned by the organization detailed during signup, if this is a legal entity. If the organization is unincorporated, the account is owned by the individual who signed up for the account.
When you sign up and create a Sonar account, the person who originally signed up for the account is default designated the primary Account Owner or Manager, but the role can be reassigned. Again, unless the organization is not a legal entity, the account and data held it in, is ultimately owned by the organization.