HELP Removing a Lien before I get a Buyer

[Luis E Luciano]

HI Biggerpockets Community,

Anyone has ideas on how to remove an Involuntary Lien (Gas) on a Property. So, I walk my dog around the neighborhood and found this house with a For Sale by Owner sign in an up and coming neighborhood. I called the Number and the lady asks who are you? We get into a conversation and she tells me the following:

-Bought the property in 2007 for $18,000 from the Districts Attorney Auction.

-I checked the records and Property taxes are up to date.

-LIEN IS $17,000

How do you remove or negotiate down a lien? She said when she bought the property her paperwork stated its was free and clear from any liens.