Why did Robb Demarest quit GHI?

Answer 1

The only info I managed to dig up on the whole situation is that Robb didn't like some of the changes Pilgrim Films was throwing into the show, so he left as a result. Unlike the original TAPS Team, GHI is owned by Pilgrim films, and Ghost Hunters is completely independent from GHI. GHI was created away from Ghost Hunters, people were just contacted about joining an international team and if they chose to come they could.

GHI is subjected to change constantly by Pilgrim films along with GHA (Ghost Hunters Academy). Ghost Hunters is the only show that is free from any changes by a major corporation since they are the start of it all.