You connected to instances to sync data between them but you are wondering if there is a way to undo the pairing process.
SAP SuccessFactors HCM Suite
Currently there is no option in UI to delete existing pair, however Engineering Team can proceed with this request under your previous formal approval in the incident.
However Engineering Team reported that they are expecting to include such functionality on the next SFSF b1908 release.
2088055 - Instance Synchronization Feature Guide & need to know information - Platform
instance sync, connection, data sync, sync , KBA , LOD-SF-PLT , Foundational Capabilities & Tools , LOD-SF-PLT-SYN , Instance Synch , Problem