Unless I'm not understanding you correctly, "useless" is a relevant term. Useless to who? Some people think certain sets are trash that others don't. Eah set has an intended purpose, and sets that aren't BiS now might be in a future update, or still worth holding onto.

You need to decide for yourself what sets are trash to you.

https://www.esoui.com/downloads/info266-JunkBuster.html

You will have to manually add what sets you want to mark as junk and then they will appear in the junk tab of your inventory instead of in the armor/weapon tab. You can also set this add on to automatically vend junk, meaning when you interact with a merchant it will sell everything marked as junk for you.

Some sets are definitely just garbage or not really worth having and always have been. Do be careful though. When I was new at this game I deleted a lot of stuff that wasn’t currently worth using but that later on became good due to changes. My advice is that if you have to delete sets that look like that present decent bonuses but don’t make much sense at the time, get rid of the armor but keep any good weapons or jewelry as those are often the most difficult to come by. Armor is generally easier to farm.