First, make sure that you are in the Edit mode of the Filters pop-over (this means that Edit does not appear in the upper left of the pop-over).
If the select option is not available for a Filter (empty circle doesn't appear to the left of the Filter), that means that you are currently in that Filter and it is "active". It is not possible to select "active" Filters to copy or delete.
To make the Filter available for copying or deletion, select Done to exit the Edit mode then select a different Filter (or select 'No Filter'). Once in a different Filter, select Edit and your desired Filter should no longer be "active" and now be available for selection.