Deleting files without extension from each folder group

[edwardsjethro]

I want to delete files without extension from each folder group.

It's the same file, but normally there is a file with a jpg extension like this.
And there are files with random numbers without extension.
I want to select only files without extension, how can I do that?

[DigitalVolcano]

You can do this with the selection assistant:
Set to "All but one matching set in each group"
Preferring to mark:
"File Name" -> Does not contain -> .