Spreadsheet
✔ spreadsheet was sent
Slide spreadsheet name to the left.

Spreadsheet Row
Tap on row
Tap REMOVE button
YES to send to recycle bin

Spreadsheet Column
Open spreadsheet properties
Slide column name to the left
OR
Open column, tap REMOVE button

Empty Recycle Bin
Open recycle bin
Tap trash can button
YES to empty and delete all permanently.