RenameTopoGeometryColumn — Renames a topogeometry column
topology.layer RenameTopoGeometryColumn(regclass 
                        layer_table, name 
                        feature_column, name 
                        new_name);
This function changes the name of an existing TopoGeometry column ensuring metadata information about it is updated accordingly.
Availability: 3.4.0
SELECT topology.RenameTopoGeometryColumn('public.parcels', 'topogeom', 'tgeom');