Is there a proper way to get someone off the stage at open mic nights?

Either the old Vaudvillian shepherd hook yanking him off stage or have somebody throw a beer bottle or two at his head.

Edit*

You could also get the emcee or whoever runs the open-mic to interrupt the middle of the guy's song and be like "That was joe-BLOW! Thanks guy."

Open mics suck. They really do. It's a venue for hack and terrible musicians like me to practice our performance on instruments we can't really play. I go to open mics and play my guitar. I get paid to play my bass. Big difference.

Here's the thing. Something needs to happen.

(1) The MC enforces a song limit. Solo artists get 2 songs. Bands get 4.

or

(2) The MC places this guy absolute last in every single lineup. This is a more passive aggressive approach. Meaner, but if your MC is too afraid to enforce the rules this may be easier for him.

or (3) At least he's playing after you and making you look good rather than playing before you and scaring away your audience. Bonus points to musicians who suck but not enough to scare away the crowd before you go on though. They make you look really good.

Here's what I'd do: Talk to the MC. Tell him you want to play the open mic every other week instead of every week. That you want to do 5-6 songs each time. You're a full band with amps, drums, etc... It's a huge hassle for you to haul gear and do setup and teardown. If each of you did solo sets you'd go on for an hour. As a group you're doing half of that. That's the most important thing. Later on tell him that he needs to deal with the out of control country dude.

I wouldn't do a free weekly gig for 2-3 songs of exposure. Tell him you deserve 5-6 for being a full band.

It's exactly that, and 'open' mic. He has just as much right as you. However, the host should step in and limit him to the time constraints placed on everyone.

You did say it was "open" mic night didn't you? So what's the problem. If you guys don't like it then go play real gigs instead of open mic nights.

Throw an empty beer bottle at him from somewhere in the crowd where he won't be able to tell who did it.

stop and say sorry we all have to really take a break and then go slowly over to the person and buy him or her a drink and tell them time to time we really have to do this thanks but make it short next time hopefully they get the hint

get the bar owner to give this guy a shove offstage, so to speak.