One of the first screens you will encounter in the Minnesota interview is entitled "Tell Us About Any Income Adjustments".
The second line on this form says, "Received compensation from a Military Pension or other Military Retirement Pay.".
Check this box.
This will open two lines that say
Enter the amount of your Military Pension or Retirement Pay
received in [the current tax year]
Enter the amount of your military pension in the box on the second line.
This will remove your military pension from your Minnesota taxable income.
[Edited 3/17/2020 3:53 pm CDT - made year neutral]