You are unable to find the functionallity to merge business partners.
Either because a business partner was created accidentally, or an unwanted business partner was created from the organization management, you want to merge two business partners.
SAP Business ByDesign 1711
It is not possible to merge business partners in the system.
Even if no transactional data was created yet, this feature is not available at the current version.
This is the expected behavior of the system.
KBA , AP-BP-BP , BusinessByDesign: Business Partner , Problem