I formatted an SSD destined to become my new High Sierra boot disk as APFS, not realizing that HFS would have been fine. Is there any way I can re-format this drive to HFS+? They ought to issue a warning before formatting a drive as APFS, to the effect that Disk Util can re-format HFS as APFS but not APFS to HFS. Is there any command line way to completely erase APFS format and start clean?