Depends on the extraction plan you set up with the guide. Is he coming to get you. Are you walking out to road to meet him. Best to notify him if he is coming close to meet you and waiting for you to walk out that they are on the bait and he can walk in making noise and shining flashlight and they will leave.
If you are scheduled to walk out yourself to get picked up and can't get word to guide that there are bears on the bait I would let them know I was there and most times they will leave. If they don't it may be a long sit it they will leave.
If you don't show up at pick up point on time the assumption should be you are still in tree and guide will come in.
It all Depends I what you agreed to ahead of time in your contingency planning as this is not an unusual situation
I hunted over and elk carcass a few years ago and a sow with 2 cubs had claimed it. It was a real PITA when it was time to leave, I make some noise, tossed some branches at them. The cubs would just climb a nearby tree. But finally I just gathered my stuff and started my decent. The bears moved off just a ways looking at me, with me moving in the other direction..
I would say the toughest part of this is that until you are on the ground with the bears they don't consider you enough of a threat to leave. You can often yell and throw sticks at them all night from the tree stand and they may not want to leave. If you are scared I think it comes through in your voice and actions, makes them more bold. On your own you just have to confidently climb out of the tree, weapon loaded and walk out of there, don't climb back up just because of a bluff charge. Of course you need to be able to recognize the difference between a bluff charge and real charge, you'll really know when you got it wrong. Good luck!
Take out your Rubber Blunt and shoot the sow in the rump! I'd try to scare them off sooner than later, no point in non-legal bear eating up all the bait, especially in CO where its illegal to bait and an elk carcass is golden.
Is the trail going past them or are you walking away. If I don't have to go though them I just climb down and walk out. The momma will usually act tough and bounce on her front paws, maybe snap her teeth. But it's all show. They want the bait. Not you. And if your bait isn't tastier than you, get a ne guide ??
I think we need to identify if these are "this year's Cubs" (typically smaller than a 5 gallon pail), or a year and a half old (juvenile) bear.
If it's a cub I'd stay quiet until they've had their fill of the bait and leave of their own accord.
If their juveniles and if you've got to walk out to an extraction point you may need to prompt them to leave by making some noise, tossing a rock or limb their way, etc. Either way I'd text or forewarn my guide you had bears or bears with Cubs at the bait. If he's coming in on a quad or ATV the noise "should" prompt them to leave the area.