Hello! I would be happy to help. Here are two videos from member of our community that walk through setting up autofil/autocomplete: video 1 and video 2 . This forum thread may also be helpful as well.
In regards to being able to remove items, you can set this up by setting up a workflow for the the element that displays the group name. This element should have a remove button that, when clicked, removes that group from the selected list and back to the autofill list. I hope this helps!