The Blueprint Update includes the ability to archive items that you do not want to see in your inventory. These items are added to the Archive tab.

Archive is a new tab in the Manage Inventory and Player Trading screens. Players can hide items they don’t want to see. When an item is archived it will only show on the Archive tab. Archived items will no longer show in Manage Inventory, Garage, or Player Trading tabs. 

You can search for items that are Archived by selecting the Archived option from the Filters Drop Down. This filter has been added to Manage Inventory, Player Trading, and Garage tabs. Archived items can also be Favorited.

Items marked to Archive will show on your current tab until you move to a new tab. When you come back, the archived items will no longer show. At that point, those items will only show on the Archive tab.

You can remove an item from the Archive tab by selecting Unarchive button.
For more info please check out, How do I Archive items?