Unless the instrument creating the power specifically provides to the contrary, a donee may at any time:
(1) completely release the power;
(2) release the power as to any property subject to the power;
(3) release the power as to a person in whose favor a power may be exercised; or
(4) limit in any respect the extent to which the power may be exercised.
Official text of the Texas Property Code as published by the Texas Legislative Council.