Once you have the full set of each outfit, and put the whole set in a character's inventory, it unlocks for that character in Collections, and you can discard the original pieces and claim new copies from Collections when you want them. The same is true of Seasons weapons, except that they unlock as soon as you receive them because "the whole set" is just one object.
That is not correct. I have the full set of MK-2[item] Yavin-Bolzenschützen and also other Armours which will not available at the Collections. I has it in the inventory and also dressed it on.
If I delete them they are gone.
For my understanding a set is : Helmet, top, legs, feet, belt, wrist, hand
It would be nice the accessories are available also.