We dont; do your homework for you - you wouldn;t learn much, if anythign, if we did!
So ... time to start reading:
Arrays (The Java™ Tutorials)[
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Because java arrays are a fixed size, you will need to maintain an index of teh "next free element" for your roles array. You can add an item by putting it in that array index, and incrementing the index.
Deleting is more complex, you will need to find the role and it's index, then "shuffle" all the elements with a higher index down one, before reducing the "free element" index.
Sounds complicated? It isn't really. try it on paper, or with playing cards acting out the part of array elements, and you'll see how easy it really is!