Take a look at NavigatorButtons of the view. You can disable/enable every one e.g.
view.NavigatorButtons.Append.Enabled := false;
or disable/anable them all in a loop:
var
i:Integer;
begin
for I := 0 to view.NavigatorButtons.ButtonCount - 1 do
view.NavigatorButtons.Buttons[i].Enabled := false;
end;