Can't Edit Excel Worksheet

It is an excel file with .xlsx extension. I can open the workbook but can’t edit the text in one worksheet.

Hello - perhaps opened “write-protected” ?

Also: The single sheet might be set protected.

how to remove the protection?

The dropdown menu of the sheet should contain an item Protect Sheet…..
-1- If the sheet isn’t protected, you get a dialog offering to protect it. Your problem must have its origin elsewhere in this case.
-2- If the sheet is protected with the empty password, the protection will simply be removed.
-3- If it is protected with an actual password, you need to enter the PW. Since you obviously don’t know it, you need to get more detailed help about removing sheet protection by file manipulation. I personally never did it for any Excel file.
Anyway I would save a copy of the document in LibO native format first.

It seems like this worksheet is password protected, so you can’t edit it, right? if so that,the password? When you were trying to edit it, it didn’t ask you for a password?
Cracking it with this program:
https://www.androidphonesoft.com/resources/unprotect-excel-sheet-without-password.html