In NXT Analyze it is currently not possible to exclude archived gifts from reports. We archive gifts when we need to make a Gift Aid adjustment. The system then prompts you to add a replacement gift. In this instance, the replacement gift is a duplicate of the archived gift therefore you need to exclude them from your reports or your report totals are incorrect.
There is another Idea from last year for filtering Written Off pledges from Analyze, too. I believe they're related suggestions and very necessary!