I'll share a past experience I had, but it's not 100% applicable to your situation.
I had PMI on my first home. As soon as it hit 79.9% LTV ratio, I called my lender and asked them to remove PMI. They told me that I had to pay for an appraiser of THEIR choice to come do an appraisal to verify that my LTV ratio was, in fact, less than 80%. It seemed to me that their hand picked appraiser may have an incentive to undervalue the home, so I didn't go through with it.
The lender is required to remove PMI at 78% LTV ratio. I did the math and the cost of the appriaisal was actually more than the amount I was paying in PMI between 80% to 78%, so I just waited a few more months and asked them to remove it once they were required to.