You can use "AjaxControlToolkit.PopupControlBehavior.__VisiblePopup.hidePopup()" to close the popup. e.g.-
<a onclick="AjaxControlToolkit.PopupControlBehavior.__VisiblePopup.hidePopup(); return false;"> Close </a>
Close PopupControlExtender using javascript
Sometime you may need to close the PopupControlExtender programmatically, here is how you can do it.
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