Sharepoint how to accept a blank choice after the user inputs a choice column value

So a user had encountered an issue of creating a choice column but they want to set it to blank but the system does not allow them to save the blank value.

The column is A choice type with Yes/No.

• Require that this column contains a value:  No
• Choices
• Yes
• No
• Display choices using:
• Drop-Down Menu
• Allow 'Fill-in' Choices:  Yes
• Default value:  can be left blank

The user is allowed to save Yes/No or blank since the field is not required but when a user saves a value then the user is not allow to clear the selection.

so to resolve this the key is to allow the 'Fill-in' choices option to YES.

then in the validation formula:
=IF([column name]="", TRUE, IF([column name]="Yes", TRUE, IF([column name]="No", TRUE, FALSE)))

so for example:  if a field is called Have Driver License then the formula would look like the following:
=IF([Have Driver License]="", TRUE, IF([Have Driver License]="Yes", TRUE, IF([Have Driver License]="No", TRUE, FALSE)))