Deleted records still in global search

I use $bean->markdeleted() to delete contacts but I find they are still appearing in the global search afterwards and then when clicked it says data not available (because they are marked as deleted in the DB).

Why does the markdeleted not remove them from the elasticsearch index - is it a config setting or bug?

do I have to do something else to remove them afterwards? 

Is there a command/script I can run or does it require a full reindex everytime?

Using 8.0.1 with Elasticsearch 6.5