What should the questioner do with an incense box she found in a drawer in her new office and cannot hand over to the administration?

If the container is valuable, you must search for its owner to return it to him, and ask for forgiveness or pay the value of what you consumed from it. If you do not find him, then give in charity on his behalf the value of what you consumed, and leave the rest in its place. However, if it is trivial and people do not usually care about such things, then there is no harm in using it.