Open the document editor by tapping the grid button at the top right
Make sure you are in the edit mode. To switch to the edit mode tap the edit button next to the grid button
Select one or multiple pages in the thumbnail grid. Selected pages are marked with a colored check mark. The actions will be enabled as soon as you have a selection
Tap the minus button at top left
Save by tapping the checkmark button at top right and choose a save option
Note: Any changes that are not confirmed will be lost when leaving the document editor!