To edit a movie, select it from the Main List then tap the Edit icon in the top right corner of the Detail Panel.
You are now in the Edit screen.
Make the changes you wish to make, and hit OK (bottom right corner) to confirm:
You can use the arrows in the bottom left corner to move through a list of movies.
Tap the cover to make changes. You can learn more about covers here
You can delete movies by swiping on the title from right to left.
Using the same method you can also delete a folder containing multiple movies.
If you wish to delete your entire collection, tap the Settings icon:
In there you will find an option to ‘Empty Database’. Tap it to delete all movies from your collection. The app will ask you to confirm.