Important: If you turned on iCloud for Numbers (in Settings on your iOS device), deleting a spreadsheet from iCloud removes it from iCloud and from all other devices and Mac computers that use the same iCloud account.
In the spreadsheet manager, tap Edit.
When the spreadsheets begin to jiggle, tap the ones you want to delete.
To deselect a selected spreadsheet, tap it again.
Tap 
, then tap Delete Spreadsheets.
To cancel, tap anywhere in the spreadsheet manager background, then tap Done.
If you open an existing spreadsheet, edit it, then decide you don’t want to keep any of your changes, you can revert the spreadsheet to how it was when you opened it.