I know a mechanics lien is not enforceable after one year on residential property? Does that mean I will be able to sell the property if the lien is no longer enforceable or will the title company make me clear the lien?
Short answer: No. A title company will not likely accept the risk of a lien on the property.
If the lien is invalid for whatever reason, you can write to the lien claimant to explain why the lien is invalid, and demand that the lien be released.
You really should retain a construction attorney to review and evaluate your legal position based on the contract and pertinent documents. The right to be entitled to file a mechanic's lien is set out in Texas Property Code Chapter 53, and you really need to make sure that the lien has been properly and appropriately filed, or if not, why not.
Filing an invalid lien could subject the lien filer to liability under the Texas Fraudulent Lien Act, and the lien filer could be liable for statutory damages of $10,000, or actual damages, whichever is greater, plus attorney's fees.
Good luck.