I have a friend who just signed up to Empire Minecraft and was assigned to SMP6. He wants to know what is the procedure to change his residence from SMP6 to SMP3 (where I am).
Just do /res unclaim. Then, he can come to smp3, find an open or derelict plot near you, and do /res forceclaim. Bear in mind that if he's claiming a derelict plot it will cost 5k
If rupees are an issue, do this first. These residences are free. If you are going to forceclaim a residence for 5,000, then I recommend you check to see if a neighboring plot is derelict, or able to be forceclaimed.
If you have a bit of luck, there will be a residence next to you that is derelict. Forceclaiming it would cost 5000 rupees, but it also means that your residences would be next to each other.