TFS: how to change custom field allowed values

I have my custom field of string type with predefined set of values: "1 - Cool", "2 - Good", "3 - Average",...

Now it is necessary to remove "2 - Good" value and rename "3 - Average" into "2 - Average".

I see easy solution: just delete 2 existing "2 - Good" and "3 - Average" and create the new "2 - Average".

Question:

Q1: What will happens with issues that contain values to be deleted? Probably, system won't accept such work item ch开发者_开发技巧ange?

Q2: What is a good approach to do what I need?

Thanks a lot! Any thoughts are welcome!

A1: The value in the work items is stored as test, so changing the WIT won't change the value for existing work items. You will get an error if you open a work item with the value 2-Good and try to save it. The user needs to choose a new valid value before the wi can be saved.

A2: You can use Excel to do a bulk edit of all the work items and modify its values to get a new valid value.