Справка LibreOffice 7.5
Protects the sheet structure of your document from modifications. It is impossible to insert, delete, rename, move or copy sheets. Open the Protect spreadsheet structure dialog with Tools - Protect Spreadsheet Structure. Optionally enter a password and click OK.
The structure of protected spreadsheet documents can be changed only if the Protect option is disabled. On the context menus for the spreadsheet tabs at the lower graphic border, only the menu item Select All Sheets can be activated. All other menu items are deactivated. To remove the protection, call up the command Tools - Protect Spreadsheet Structure again. If no password is assigned, protection is immediately removed. If you were assigned a password, the Remove Spreadsheet Protection dialog appears, in which you must enter the password. Only then can you remove the check mark specifying that protection is active.
Защищённый документ можно сохранять только при помощи команды меню Файл - Сохранить как.
You can create a password to protect your document against unauthorized or accidental modifications.
You can completely protect your work by combining the options Tools - Protect Sheet and Tools - Protect Spreadsheet Structure, including password entry. If you want to prevent the document from being opened by other users, select Save With Password and click the Save button. The Enter Password dialog appears. Consider carefully when choosing a password; if you forget it after you close a document you will be unable to access the document.