Editing a Filter is pretty self-explanatory, you can delete logic by clicking the trash cans, and you can remove tags by clicking the X in the tag. You can add additional logic by clicking the + button.
A couple of points to remember:
Tags have to already exist to be used in a filter. You cannot create them in the filter as you can in Checklists, Users, etc.
The results will not update as you are editing. You will have to click Save Filter and then come back to see the results update.
Changes to filters and their results will instantly go into effect once the Filter has time to recalculate. If you remove a person from a User Filter, they will no longer be able to see that location anymore.