Changing a field from True/False to String - is it possible?

Not applicable

Hi, 

We created a custom field in the table [rm_release] to allow us to capture information for our teams, however, now the business would like to amend this field type from type = True/False to a String with Choices (yes/no) and make the field Mandatory.
Unfortunately, when trying to amend the type in the dictionary entry, not all Types are showing. 

find_real_file.png

I've seen suggestions on other posts to add a new field, remove the original from the form and map current values as a parent.
However we're trying not to bring more fields into the table and it feels like this is something we should be able to do, but I am missing something.

Any help suggestions would be appreciated,

Aaron