"For example, I have "January", "JANUARY", "january", and "jaunary" in the same value list"
To clean-up those entries, you have to clean-up the values of the "from" field.
Thank you, Raybaudi.
However, how do I clean-up the values of the "from" field? This was my initial question.
Go to the table that the values come from.
Go into 'Find' mode. Click into the field that you want to 'clean'. Click Ctrl+I or Cmd+I (or Insert | From Index...) and choose the value list item you want to remove.
Perform the find.
Change the erroneous values in the records you find to be the correct value. Use the 'Replace' menu option if there are a lot. USE THAT WITH CARE, as always.
That 'bad' value will no longer be in the list.
Repeat with the others, until the value list you see with Ctrl+I looks the way you want it to.
Thank you Sorbsbuster! That was too easy a solution. This forum is the greatest!