The 'wname' is the name of wavelet from the Wavelet Toolbox. http://www.mathworks.com/help/wavelet/ref/cmddenoise.html#inputarg_wname
Based on your application, you can use the available wavelets in the Toolbox. These are all the wavelets that come with the toolbox:
https://www.mathworks.com/help/wavelet/ref/waveletfamilies.html
If you don't know which specific wavelet to use, you can test your application using the wavelet app. https://www.mathworks.com/help/wavelet/gs/introduction-to-the-wavelet-families.html
There is a functionality to add your own wavelets to the toolbox. If you want to use your own wavelet families with the Wavelet Toolbox™ software, do the following:
1. Create a new directory specifically to hold the wavelet extension files.
2. Move the previously mentioned files into this new directory.
3. Prepend this directory to the MATLAB® directory search path (see the reference entry for the path command).
4. Use this same directory for subsequent modifications. Allowing many wavelet extension files to proliferate in different directories may lead to unpredictable results.
5. Define an MATLAB file called <fsn>info.m (for example, see dbinfo.m or morlinfo.m), which will be associated automatically with the Wavelet Family button in the Wavelet Display option of the graphical tools.
Here is a comprehensive discussion of creating user defined wavelets: https://www.mathworks.com/matlabcentral/answers/75397-adding-custom-wavelets-to-cwt
