how to remove cache duration from code-behind?

I have used [WebMethod(CacheDuration=1200)] in my webservice method, however I would like to remove cache programatically from the code behind of aspx page

how would you do that ?


Example:

 [WebMethod(CacheDuration = 1200)] //<<<<
    public CascadingDropDownNameValue[] GetCountry(string knownCategoryValues, st ...