You can reassign your contacts to a new agent at once. Note that this will reassign all contacts you have done a search for regardless of who they are assigned, to another agent of your choosing. To do this, go to CRM → View Contacts
Perform a search for the contacts you would like to reassign. After searching, select the contacts you wish to reassign. If you do not select any contacts, the Reassign All button will reassign all contacts in the search result.
Then select Actions → Reassign All
Choose the agent, office, and team that you want the contacts to be re-assigned to, then click Okay.
A green confirmation message will pop up at the top of the screen saying that your contacts are reassigning and you will get an email once it is done.