The behavior that you are describing is a browser behavior not related to our controls. IE browser will add the small "x" button to all input elements, when they are focused. What this button does is to clear the content of the input element. Please note that this icon is not available in other browsers like Chrome or Firefox, it is only IE feature.
I would suggest that you hide the clear button in IE also. The following forum thread demonstrates how to achieve this in IE10:
Once again, please have in mind that this is a IE behavior, not related to our controls in any way.
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.