Format APFS external drive to HFS+

I upgraded to High Sierra - first mistake - and having read all these wonderful things about APFS, reformatted two external drives to that format. However, after having a lot of issues with High Sierra, I learned that external drives shouldn't use APFS, only internal SSD drives. Funny how Apple didn't prevent me from doing it.

Anyway, now I want to reformat them back to HFS+, but when using Paragon ExtFS for Mac v11, while an option, it returns with an error (no message id number) and nothing happens.

Within Disk Utility the only options for formatting are APFS on an existing APFS drive.

Any help or advice would be appreciated. Thanks.