In Schedules, you are able to change the Field Type for a Custom Field. However, keep in mind, that when a field type is changed from one type to another, there are some implications to your data.
Below is the list of changes and the implications that occur:
Number ➝ Text: Converts the numbers to text
For Multi-Entry Fields: numbers become a comma separated list of values
Number ➝ Attachment: Deletes all values
Number ➝ List: Changes all values to list options
For Multi-Entry Fields: every value becomes an option
List ➝ Text: Converts the list options to text
For Multi-Entry Fields: list becomes a comma separated list of values
List ➝ Attachment: Deletes all values
List ➝ Number: Deletes all values
Text ➝ List: Deletes all values
Text ➝ Number: Deletes all values
Text ➝ Attachment: Deletes all values
Attachment ➝ List: Deletes all values
Attachment ➝ Number: Deletes all values
Attachment ➝ Text: Deletes all values