The Protect Sheet or Protect Spreadsheet Structure commands prevent changes from being made to cells in the sheets or to sheets in a document. You can optionally define a password. If a password is defined, removal of the protection is only possible if the user enters the correct password.
Choose Tools - Protect Sheet.
Choose Tools - Protect Spreadsheet Structure.
Protects the cells in the current sheet from being modified.
Protects the sheet structure of your document from modifications. It is impossible to insert, delete, rename, move or copy sheets.