Trump did not discuss the wall/payment....the Pres. of Mexico brought up the subject....Trump did not respond. That means there was no 'discussion'. A 'discussion' implies that there is a back and forth exchange.....there was not. Your apology is accepted.
There are probably lots of ways, some of which are impractical, and some of which are reasonably easily implemented.
I wouldn't be surprised if we send money to Mexico for purposes that would permit us to reduce the amounts sent and re-direct them to border security. That sounds exactly like the kind of result Barack Obama would use an executive order to accomplish.