I cannot delete sheets in calc. File has 5 sheets. When I delete sheet 1 and 2 it seems to delete the sheets, but next time I open that calc spreadsheet those two deleted sheets are back. How can I permanently delete sheets of a spreadsheet file?
Please state clearly if you saved (stored) the document after having deleted the sheets.
Be sure to understand that the contents of the deleted sheets will be definitely lost after the writing to the file if there is no backup of the document in the previous state.
If you want to keep the contents, but not to show them normally, you can hide the sheets.
For future work all these operations ony take effect if the document was stored again.
Choose Tools - Options - LibreOffice Calc - Defaults. There you “can set the number of worksheets in a new document, and the prefix name for new worksheets”.