The remove header row is an open issue in Vaadin: vaadin/flow-components#1538
It woud be useful to have them in order to "reset" the grid, or at least that's the use I would give to this feature.

A workaround for the header: vaadin/flow-components#1538 (comment)

For the footer you can do
grid.getColumns().stream().forEach(col -> col.setFooter(""));
and the footer will be empty, but the row will be still visible.