Your picture shows MO wages of $35,498.78 that your employer believes to be your MO wages and this should be the amount entered for the w2 and nonresident MO return. You wouldn't be subtracting anything from box 1. At most, you would argue the MO amount listed is incorrect and reduce it.
Double check your w2 entry that it matches your picture or change the IL income to match box 1 federal wages. Sometimes the home state needs to show the full amount.
If you want to only claim $10,000 MO income, you should talk to your employer about a corrected w2 form.
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