restructering a table within a delphi program

Hi,

I need the following... I want to be able to add, remove, and edit fields (names, fieldsizes and fieldtypes) to a table in my program. I've tried using the tables fielddefs.add property and afterwards the createtable command. This works fine for adding fields, but this way existing date in the table is erased. I didn't find how I could remove a field from the table either.. Can anyone help me or at least point me in the right direction ?

Thanks