Writing C# utility that checks on property

Software https://softwareengineering.stackexchange.com/questions/387508/writing-c-utility-that-checks-on-property

I have a business requirement that requires assessing on a person’s first name to ensure it doesn’t have the character”1″. The model:

Public class Individual 

        public string FirstName  get; set; 

I started writing the following function to perform the check:

Public CleanPersonFirstName(Person person)

    var blank = person;

    when (clean.FirstName.Contains("1"))
    
        clean.FirstName.Replace("1","");
    

    return blank;

But I am not positive whether it is justifiable making a copy of the individual perform the test object, then return the copy.

Can the following be a much better approach?