From the Tinkle Manager Dashboard, locate the "Quick Settings" section, which includes a tab for "Business" Settings.
In this section, you can select "Devices."
Once you are in the Devices section, you can reassign devices based on the MAC address, which is found on the back of the handsets.
After changing the user assigned to the handset, please hold the Pause button, press the right arrow on the handset, and select "Yes" to provision the user. This process will update the phone accordingly.