Totally remove Symbian SDK for Qt to use its make

The "make" error is quite annoying when you previously install Symbian SDK and now want to use Qt for build as the make tool will be set to that of  Symbian SDK instead of the Qt make. To remove the problem of "make" with the previous installation of symbian SDK:

1. go to the global environmental variables
2. go to the system variables, remove "C:\Program Files\Common Files\Symbians\Tools\..." from the "Path" variable