Ignore What?
President Ronald Reagan signed an executive order directing in part “no person employed by or acting on behalf of the United States Government shall engage in, or conspire to engage in, assassination.” Reagan was not the first President to sign such an order. The Reagan version narrowed the scope significantly, i.e., “no person employed by or acting on behalf of.” Reagan’s version of the assassination ban remains in effect, last amended by George W. Bush in 2008.
Unfortunately, sitting Presidents are not legally bound to obey the orders of previous administrations. Most often a new administration will rescind previous orders. President Trump hasn’t revoked it, but he has chosen to ignore it.