If you have your front speakers set up properly, you really wouldn't need a centre channel at all. The stereo imaging would place the people and their voices where they should be.
If you do eliminate the centre speaker though, you will have to tell your processor to go to phantom mode. If you just disconnected the centre speaker without going to phantom mode, the processor is still going to send all the L+R signal to the center output. With no centre speaker attached, the voices will then disappear for the most part. The instructions for the particular processor should tell you how to do this.
If you do eliminate the centre speaker though, you will have to tell your processor to go to phantom mode. If you just disconnected the centre speaker without going to phantom mode, the processor is still going to send all the L+R signal to the center output. With no centre speaker attached, the voices will then disappear for the most part. The instructions for the particular processor should tell you how to do this.