Currently there is no way to hide or disable parts of the insert hyperlink dialog. However it is relatively easy to create and use your own dialog by implementing the new slightly changed IInsertHyperlinkDialog interface. I've attached a sample project that demonstrate this. You can use it in your project and customize or remove all the parts you want.
You can see that in the example the MyInsertHyperlinkDialog class has the CustomInsertHyperlink attribute. This way the rich text box will automatically detect it using MEF and will show an instance of this dialog when you call the ShowInsertHyperlinkDialog method.
The other way to replace the default hyperlink dialog is to explicitly set the InsertHyperlinkDialog property of the RadRichTextBox control to an instance of your custom dialog. In this case you don't need to add CustomInsertHyperlink attribute to your implementation of the dialog.
I hope this was helpful. Don't hesitate to write to us again if you need further assistance.
the Telerik team
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