Queue Details tab

When you in the Queue overview tab have clicked on a number in column "In queue", you will see Queue Details view, which shows a list of the requests in this queue.

If you have enabled the "pick" from queue feature, you can pick a request from the queue details by clicking on the pick (arrow up) button.

If you pick a request from queue, you set yourself as the "reserved agent", and this request will be shown in your Personal queue tab, and it will be allocated to you now (if you are ready) or when you become available.  

After you have picked a request and it's shown in your Personal queue tab, it will also be shown in Queue details for the queue it is in, with a "Release request" (arrow down) button. As long as the request is still in queue and has a reserved agent, both you and other agents can click the Release button to remove you as the reserved agent.