How to delete:
Deleting an issue will remove the download from your device, freeing up space. You can download it again at any time in the future. To delete an issue go to My Library then tap the 3 dots below a cover and select delete.
Archiving:
You can move editions out of your main My Library folder by tapping the 3 dots below a cover and selecting 'Archive'. You can retrieve editions by tapping 'Archived' in your library and unarchiving them in the same way.
Auto-delete of Plus+ downloads:
To free up space on your device, Plus+ downloads will auto-delete if they have not been read for a certain amount of time (default 90 days). You can change this, or turn it off, by tapping the Options button then 'Manage Downloaded Issues'.
Bookmarks:
Any bookmarks you have saved can be viewed by tapping Bookmarks in My Library. If the edition is not downloaded you will be able to view just the bookmarked page or download the edition. You can also delete bookmarks from here.