The most obvious choice for skp to dae conversion, i.e. SketchUp to Collada conversion, would be of course to SketchUp as it has support for Collada formats (Schema 1.4). This can be achieved through the File ► Export ► 3D Model function found in the program. It is worth mentioning that Collada format does not support all SketchUp features.
If you do not have access to the commercial version of SketchUp, you will have to use some of the third party alternatives or dedicated 3D model / CAD converter that will allow you to convert skp to dae.
Updated: June 21, 2023