A patch or something the person themselves controlled would be ideal. Most of what I can do, I can do for myself - presuming its effective at all - but doing it for others, or on others, is going to require a lot of mental energy, so maintaining it - difficult.
Removing memories after they're there is I think all around something we're all going to have more experience with. You could possibly bait and switch it, like - it's the basic technique behind the 'Jedi Mind Trick' thing. You trick someone into focusing on something else. It doesn't take away the thing usually (it can, but most of the time you don't need to be that specific because humans are generally pretty easily distracted), but it focuses them onto a different context so it doesn't make the impact it would otherwise.