Hi bergyver,
My apologies for the delayed response on our end, more than happy to help out!
After some quick testing on my end, it appears that you are not missing something - this is a bug on our end. On other similiar actions, Update Fields in Table for example, you will see 'Loop' as a selectable value in the 2nd Value Dropdown - See;
Now it appears this same option is missing from the Delete Records from table action.
This being said, there is a quick and easy workaround to get this one up and running, using an Action Result. You Loop through the grid. assigning the Record ID of the current record in the loop to an Action Result, and use this action result as the criteria for the RecordId to delete in your Delete Records from Table action
Hopefully this helps. Let me know if you would like any more clarification on this one.
-Ben