I retired April 2019 and I didn't pay the estimated payments for this year's returns, what do I do

Nothing to do about it now.  Actually the IRS or state won't be expecting estimates.  They are optional to pay.  Whatever is due you will pay it at the end of the year on your tax return.  

If you did not pay estimated payments and you owe tax for your 2019 tax return, you have until July 15, 2020 to pay your tax due.  Or you can set up a payment plan.

https://www.irs.gov/payments/online-payment-agreement-application