I suggest to support the ends of the box awning with a pair of 2x4s. Add a 12" bottom foot to each board to stabilize them in the shape of an upside-down "T". Wedge them at a slight angle under the awning to support it while you dismount it. Once loose, carefully carry the awning down your ladder. I just don't know how heavy the awning is.
When down, I would quickly fill all holes with clear silicone caulk to seal against rain. When it comes to remounting the awning later, you screw right through the caulk, pre-drill if needed.