I was in the same boat and was wondering how I could change my Cost Basis in Turbo Tax to say I made no Gain by selling those shares (to cover for taxes). I was able to enter the "Corrected Cost Basis" which is on a Supplemental Page on my 1099-B and enter that instead of 0.
Use this thread to understand the steps to be taken:
https://ttlc.intuit.com/questions/4645990-i-got-rsu-s-after-deducting-taxes-total-income-on-my-w-2-s...
