simply stop wallet, insert new blockchain, restart ...
I would wait for a team member to verify this, but I am on correct chain and I can 7zip block chain and make it available to whomever needs it ... I would also delete peers.dat before restart wallet ... depends on which os u are on, on windows default location is in a obscure location, /Administrator/Appdata/roaming/Diamond, on linux in /home/username/.Diamond

A FAQ is definitely is need linked on BCT OP and DMD website ...