If I understand it right, you are assuming that in the beginning we had CO2, which was then split to organic carbon and O2 via photosynthesis. And now you are asking if it's possible to reverse all of that by burning all organic carbon, so that it consumes the O2.
Your assumption is not quite right. Oxygen is the most abundant element in Earth's crust and mantle, locked up in rocks. Rocks are made out of mostly oxygen. Atmospheric oxygen is negligible, when looked up in the context of the entire Earth. Oxygen is constantly being consumed and produced by reactions between the atmosphere and the solid Earth.
Not only that, there are processes in the Earth that take sediments and pull it down deep into the Earth, in subduction zones. Anything can be subducted: both organic unoxidised carbon and oxidised carbon in the form of carbonates (e.g. limestone). This goes down to tens to several hundreds of kilometres, far away from any interaction with the atmosphere.
As an example, let's say that you have a forest which that consumes a certain amount of CO2 and H2O, generating organic carbon-hydrogen and releasing the excess O2 to the atmosphere. Now you have carbon (and hydrogen) locked up in solids. Some of this organic material burns, decomposes, or otherwise reacts with atmospheric O2 to generate CO2 and H2O all over again. However, some of it is buried deep in the Earth's crust (that's how we get coal, gas and oil). So in theory, we can extract and mine everything, and then burn it. However, some of it is buried even deeper and is carried down by subduction to the Earth's mantle. In there, it is far away from our reach and there is no way we can extract it to burn it. So the oxygen generated while producing this organic material lingers in the atmosphere, but the organic material itself is deep below in the mantle, unable to react with any oxygen (as O2, any redox reactions are a different story).
To sum it up, your point of view is too simplistic as it does not take into account the Earth as a whole, but only top soil and atmosphere.