I love topics like these - it's like running mental exercises, taking others people's views and challenging them against my worldview (a collection of these views where I selected the one I believe best, yet is always subjective to change).
If our thought had the potential to create something in reality (say, a cup of tea), as in thinking of a cup of tea was able to project a cup of tea into reality, then the reverse would be logically possible. You could think of nothing, project nothing into reality, and everything within your scope of influence (e.g. The amount of reality you can perceive at one time... Everything you see in front of you?) could wink out of existence like some kind of anti-matter annihilation event. Just food for thought.
Another aspect that you might consider is that your level of cumulative knowledge would limit not only your control of reality but also could potentially cause disaster to occur inadvertently. When driving, you might wonder how all the mechanical components of the vehicle work together to allow you to drive, and in your lack of understanding you might influence something the wrong way and cause the vehicle to break down. And the knock-on effects that follows, e.g. The car crashing into another and collateral damage... The brain is not capable of processing the entirety of that information all at once, at the time, so where does this control go to during such an event?
And then you also get the suspension of causality effect to consider, where if you observe something, but then your view/perspective gets blocked or obscured, and things happen that you can understand but can't directly observe, when does the effect take place. I'm referring to Schrödinger's cat experiment here. A living cat gets put into a box, and the box is filled with poison. Logically you know the cat should be dead, but until you see the dead cat, you can't confirm its current state... So it exists in a state between life and death until you open the box and find out. Poor cat...
The above can be explained by having a universal consciousness, external to yourself, that is keeping things in check... Keeping the order of reality (and causality). In Berkeley's idealism, this would be the 'universal observer' (also referred to as God's mind and external reality in other philosophies), so even things you can't see will still continue to exist, will still continue to experience cause and effect, and might still include someone sneaking up behind you to stick a dagger in your back. Just because you never observed them, and were never aware of them, doesn't protect you from getting stabbed because an external observer is always watching and making it possible to happen.
The model I prefer to subscribe to is the one others have already touched on... Rather than your consciousness affecting reality directly, it only affects your perspective of reality. Your knowledge, understanding, and viewpoints all make up a filter through which you experience reality. This is why depressed people find it easier to see things pessimistically and people in love see things with rose tinted glasses. Reality still persists and one car crashing into another will still happen no matter how much you try and influence things with just your mind. If you want to change causality, you have to use causality yourself (e.g. Stopping the crash by blowing up a big balloon between them... But you'd have to have such a balloon already at hand). Well, my explanation and example might be messy, but you should be able to understand the point. You influence your own internal reality, which is your perspective/filter/reflection of reality, but external reality is beyond that influence.
As for the idea of multiple divergent universes... It's a fun way to escape from reality, thinking that things may have turned out differently if choices or conditions were slightly altered, but ultimately without a way to jump between realities (like in the TV show Sliders, or with a proper time machine subject to paradox) then it's nothing more than a thought experiment and doesn't have any effect on the "true" reality.