You can sell the condo if the lien will be entirely satisfied from the sale. If not, title may refuse to insure it and any sale which requires title insurance will fall through. Whether you can discontinue support payments is a separate issue from whether you owe back support which would be the basis for any lien. You need to contact the agency that filed the lien to resolve it, unless you are in agreement and it will be entirely satisfied from the sale.
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