Remove text between html close tags C#

In C# i need to remove a text that could appear between 2 specific close XML tags:

So for example i have this text in a string:

</factura>]]></comprobante>

And i need to remove this CDATA close elements but this is just an example and could be other text between this 2 close XML tags.

I need to to it with Regex.

I tried this:

System.Text.RegularExpressions.Regex.Replace(_inputString, @"/(?<=<\/factura>).*?(?=<\/comprobante>)/", "");

But didn't worked.

Thanks in advance. Best regards.