How to handle excess IRA contribution?

I am over 50 and contributed a total of $20,000 which includes $8,200 for a Roth. Turbo Tax tells me I am $1,700 over the $6,500 limit for the Roth. Thought catch-up contribution limit would allow me a max of $24,000. How do I get TurboTax to allow the max so I don't have an excess? "

Plan doc says - 2017 Limits - The amt you can add annually to RSP is $18K.  If age 50 or older can also make catch-up contribs and save an addit $6K or a tot of $24K?