Yes, you can.
Just FYI, if you've already filed your 2018 return, you'd need to wait for it to complete processing before amending it.
Please see the
TurboTax FAQ "How to amend (change or correct) a return you already
filed," below, for instruction on how to amend your previously-filed tax
return.
https://ttlc.intuit.com/replies/3288565