The Convert to WSDL 2.0 command is enabled only when a WSDL 1.1 is active in WSDL View. It generates a WSDL 2.0 document from the active WSDL 1.1 document. Clicking this command pops up a File Save dialog, in which you can specify the location and name of the WSDL 2.0 file that will be generated by XMLSpy.
On clicking OK in the File Save dialog, a WSDL 2.0 document is generated and saved to the specified location, and opened in WSDL View in a new tab. The file can then be edited as required, just like any other WSDL 2.0 document.