The AfD and their supporters want to get rid of everyone who “doesn’t fit” into Germany according to their views. Legal status and German citizenship don’t matter to them at all, nor does it matter to them what happens to the deported afterwards. And everyone knows that’s what they mean.
But they can’t openly say it because that’s unconstitutional. So they use vague language about people “who have no right to be in Germany”. That way, their supporters know exactly what type of people they mean, but if an inquiry is started, they can pretend they were only talking about illegal immigrants.