It sounds like more of a logic problem than an engine problem. You want to keep track of a collectible using some sort of static integer, then increment it or track it per level whenever the player sprite collides with the collectible sprite, then destroy the collectible sprite. If you want to track it on an individual basis, you'll want to track each collectible in an array of bools.
Since this isn't a Jo Engine specific problem, any tutorial on 2d game design featuring collectible objects should do, just adjust the rendering portion for Jo Engine.
