EXCEL Disallow user to remove encryption but work on file

I have an excel 2010 file (workbook) which i have encrypted through password. I want to share the workbook with some of my junior colleagues to work on them and then give the file back to me for further working. But i do not want to tell them the encryption password. For that I have created an EXE in Visual Basic in which i have "hardcoded" the password and when you run the EXE file, it asks for file to open (with encryption password) and then it opens it.

My query : When my junior colleagues open the file, they can easily go to File -> Info -> Permissions and remove the file encryption. How can i prevent / disable removal of file encryption ?

Have you tried to do this yourself? I think you need to enter the password to remove the password

I have tried it. EXCEL does not ask for password to remove the password.

I guess I don't really understand the problem. What are you trying to prevent them doing?

what exactly do you mean by encryption

Encryption means to Protect the EXCEL file by going to File -> Info -> Encrypt and apply a password to an EXCEL file.