My method of getting rid of annoying residents who have screwed up my town layout is as follows:
Firstly, every time you see them you SPAM them with your bug net.
If they ask you to run errands - deliberately fuck them up, unless they are to benefit other residents. Open their parcels, read their time capsules and forget about your appointments to visit each others' houses. Never speak to them, especially on holidays. Then, if you don't care about getting weeds - set your 3DS clock forward a year. After Flo had gone, I found two others who built their houses in stupid places where I was intending to build public works projects - using the above strategy and then setting my clock forward a year worked every single time - when I loaded it up again, they were all GONE. :D