Amend 2016 return. Delete dependent.

I just need to revise it. I can send a digitized copy of the original. I did this return online with TurboTax. 2016. Please advise how to get online with it again. I need to avoid the interest being charged. It's been a month since I was notified by the IRS I cannot take my partner/extended_houseguest/friend as my dependent since he earns "too much" at 4800 per year.