Hello KC Cheung, 

It is possible to set MinValue as well as MaxValue for the numeric editor.

For example here is an online sample, where the min and max are for a NumericEditor are specified by another two editors. In this sample by default the Editor limited by Range is loaded with a MinValue of 0 and MaxValue of 10. 

You could set this property in Markup, CodeBehind as well as ClientSide:

In Markup it could look like:
        <ig:WebNumericEditor ID="WebNumericEditor1" runat="server" MaxValue="10"></ig:WebNumericEditor> 

In CodeBehind:
WebNumericEditor1.MaxValue = 10; 

It is also possible to set this maxValue using ClientSide. For example, handling Initialize client event:
In order to set the needed properties in Client-Side you can use the built-in functions for the “WebNumericEditor” like this:

function WebNumericEditor1_Initialize(sender, eventArgs){
sender.set_minValue(5); // set min value
sender.set_maxValue(20); // set max value
} 

What is more, you could find these properties under the official documentation - WebNumericEditor Class Members.