Is is OK to remove dust from the DSLR's CMOS (No filter or glass on top of it) using compressed air spray?
TLDR; Do this at your own risk!
The compressed gas is formed from a liquid propellant in the canister which under certain conditions can spray all over your very delicate electronics leading to short-circuits which cause lots of damage up to and including fire if the battery is shorted.
It will cool (possibly freeze) parts of your camera and that can lead to trouble and may not completely evaporate when brought back to room temperature, leaving opportunities to short smaller components at a later point.
Those risks are relatively rare if you carefully follow the directions to keep the can fully upright etc. - but if it goes wrong then you're likely to need to go shopping for a new camera... the level of risk compared to any potential reward doesn't really make it worth it.
If it's only compressed air (and not compressed refrigerant that is used in typical "canned air" products), then ideally it is no different from using a rocket blower, other than different air velocities due to the pressure of the compressed air.
EDIT: Practically, however, there are reasons to be concerned. Cheaper cans of compressed air are sometimes contaminated with oil from compressor used to can the air (For scientific optics "inert dusting gas" such as Techspray is used). Also, when compressed gases are suddenly released, the drop in pressure corresponds with a drop in temperature, which can draw moisture out of the ambient air and condense it. The moisture carried along with the compressed air can wreak havoc on electronics and damage them.
However, I still wouldn't recommend it. Personally, I don't use canned air to clean the sensor, for several reasons. Mostly, when cleaning my sensors, gentle is the word of the day. Just about every can of compressed air I have used generates very fast moving air. Dust particles in the airstream act just like sandblasting — they scour just about any surface they hit. Of course, the degree of scouring, if it's even visible, is highly dependent upon the velocity of the particle, but still... even a "microscratch" on the IR filter (or microlenses on the the sensor if the filter is removed) will be visible to photosites that only a few microns or tens of microns across, which will degrade image quality.
All the other answers apparently missed that you've removed the IR/UV cut filter from on top of the sensor. All the standard cleaning methods assume this protective glass is in place. You are in essence attempting to clean a bare printed circuit, and this is a very delicate and complex type of circuit at that.
I would recommend non-contact methods only, and definitely NOT canned air (you're highly likely to spray liquid propellant) or high-pressure compressed air (you could physically damage something). I'd suggest a bulb blower, like a Giotto's Rocket Blower. And maybe worry a bit about electro-static discharge (ESD).
See also: On Semiconductor's "Image Sensor Handling Best Practices" article.