Greg (Hollywood) who was selected out of thousand online applicants and an online vote may have possibly gotten kicked out of the house.
There are rumors that Greg may have left because he was fired from the job the castmates have. If you remember, back in Season 10, Back to New York, producers instituted a rule in which, if you got fired, you would automatically leave the house. Surprisingly, it has never happened until now.
Rumor has it, that the group are a part of a comedy improv group in Hollywood. Sort of a niche market for 7 strangers brought together, some of which probably don't want to be comedians. Anyway, Greg was supposedly not into it, and was pursuing modeling work elsewhere. He apparently was let go from the comedy troupe and was kicked of out the house.
More on this info as the story develops.