The phrase "ties down" refers to the act of binding, restricting, or limiting someone or something. The opposite of this phrase would be to release, free, or liberate someone or something. Therefore, some antonyms for "ties down" might include loosens, unties, untethers, unhooks, unbinds, unfastens, frees, and liberates. Using these words can help convey the opposite meaning of the constricting and binding context of "ties down." For example, "We need to loosen the restrictions and offer more freedom to our employees" is an antonymic interpretation of "We should tie down our employees to prevent unauthorized behavior.