The large electrical connector is pulled straight off. It'll be tight, but it'll come off.
Very often on the 190's, the speedo cable has to be disconnected from the transmission to gain enough slack to be able to put your hand behind the cluster to unscrew the collar for the speedo cable. If you can get your hand behind there to unscrew the cable, then fine. But remember you also have to reinstall the cable later, will there be enough slack to allow this? It can be tougher to get it reinstalled than to remove it is what I'm saying.