Formula to Decrease Text/Number combination by 1

Any suggestions on if you can create a formula for lowering a number within text by one?

So for example, I work in creating policies. I’m creating a merge template in Word and there’s a blank for this year’s policy number and the previous year’s policy number. The first year’s policy number is for example POL123456, the next year is POL123456-01, the next year is POL123456-02.

If the policy number is in Cell A2 as: POL123456-02 is there a way to populate it in Cell B2 as POL123456-01, decreasing the last digit by 1?