How to delete editable grid rows from database

Are you really required to delete DB rows?  This is usually not recommended from a data archival perspective, unless strictly required by your use case.  The more common (and much easier to fix) method is to have a column in your table to indicate "active" and/or "deleted" status.  That is, all rows would start out with an "IS_ACTIVE" property of TRUE, or alternatively, an "IS_DELETED" property of FALSE (either would work, it kinda depends on your style and your own project's standards).

Then when you click the "remove" icon in the editable grid row, you would simply have it flip that flag for that row, and write the results along with the rest of the rows when you next save them.  As an aside, I suggest using the Rich Text component for this rather than Image Field, because the style is more consistent with Appian and it's a lot more flexible in its configuration and behavior.

a!richTextDisplayField(
  value: {
    a!richTextItem(
      text: {
        a!richTextIcon(
          icon: "remove",
          caption: "Remove (inactivate) this row in the DB.",
          color: "NEGATIVE",
          size: "MEDIUM"
        )
      },
      link: a!dynamicLink(
        saveInto: {
          a!save(
            local!currentRow.isActive,
            false()
          )
        }
      ),
      linkStyle: "STANDALONE",
      showWhen: local!currentRow.isActive
    )
  }
)