Guild Wars 2

Is this achievement similar to the mini pet achievement in where you must have all of the mini pets at once, not half now and half later? I am asking can i sell the T1 armor after I buy the T2/T3 armor and still be able to get the title or do I have to hold on to all of it until I have every peace?
Thanks

No, you increment the achieve simply by purchasing the gear. Note that you don’t get credit for more than one of the same item, so if all your alts just love the T2 light pants, only one T2 light pants will advance the achieve.

So i can sell my old armors then?

They’re SBOA, so no

You can vend or salvage them if you don’t think you’ll want to wear them ever again.