Here is how I got plarium play to completely uninstall so that I could reinstall and update it.
Windows 8 right click the windows icon bottom left of the task bar select Run type in regedit click OK . Now you have to find the plarium play folder delete the files in it and then delete the plarium play folder. mine is located under this path. HKEY_CURRENT_USER\Software\PlariumPlayInstaller you will have to open the keys in the registry to get to this folder. delete all the files you can in the folder for example version language installfolder and default it will not want to delete the default file do it last then delete the plarium install folder. now reinstall plarium play from the plarium play exe download file if you get a new installation screen and it all loads and asks you to update to play do so. don't delete anything else in your registry keys.
Hope this helps it worked for me.