No, not directly. The way it can be done is by removing the old field and creating a new one in its place.
I've created a script that can do this with any kind of form fields:
Short answer: not really
Note that you will also have to restore the tab order, because you deleted and added fields (which is better done in Acrobat 8 or older…).
The last Acrobat version which would have allowed to change the type of a field (not programmatically, but manually, without having to delete and recreate) was the Best Acrobat Ever, Acrobat 5.
Hope this can help.