I would not do this if I were you. Formidable already allows you to change field types if the field types are compatible. A select and text field are not compatible types for conversion. What you may be able to do, and I have not tested this, so if you try it, do not do it in a production system. Don't try to change Formidable definition metadata in frm_fields. You are guaranteed to break something down the line if you do. Change the field association in the entry data instead. Create a new select field and change the field_id for the associated data in the frm_item_metas table.

Thanks Victor, I was thinking that creating a new select field and then changing the field_id might be a safer option. I'll take a look at doing that. Appreciate your advice