change them from their current varchar datatype to date and datetime datatype

Hi Guys I still have not got answer to this problem. I have 100 colums in a table which are varchar datatype. I want to change them from varchar datatype to datedatatype. these colums are datefield colums say [Vax hover delivery actual date]. so how can I change them from their current varchar datatype to date and datetime datatype. I will appreciate. thanks