Change the field data length of AET generated field in CRM

Dear All,

I want to change the field length of AET generated field in CRM. Currently length is CHAR 10 & wants to change to CHAR 20. I have gone thro many post but not clear the steps. I have also checked the thread AET: How to change Field length once field is generated?

But still confused, Please help me & also share the details steps for changing the field length.

Thanks

Abhiiesh