There have been times when adding a child from new FamilySearch to RootsMagic that NFS does not send a complete packet of information on the child.  The record received from NFS gives only the sex of the child and assigns it a record number in RootsMagic.  This child can not be added to nor deleted.  This is what we call a "Phantom Child".

To remove this "Phantom Child" you will need to create a new blank database and either Drag n' Drop your complete file to the new database, or import a GEDCOM file of the old database into the newly created database.  When the database with the "Phantom Child" is imported by Drag n' Drop or GEDCOM method into a new database, it will not bring over the "Phantom Child".