How to add a letter from my brokerage company that states that I removed excess contributions from Roth IRA? I realized I was above MAGI limit in Feb using TurboTax.

Attaching the letter is not necessary but providing explanation is necessary.  Your explanation can include information from the letter.  TurboTax will prompt for the explanation when you enter the original Roth IRA contribution and indicate to TurboTax the amount of contribution returned.  The explanation should include the date and amount of the contribution, the date and amount of contribution returned (not the amount distributed), and the amount distributed after adjusting for investment gain or loss.