This phone type is not removed from the switch port details until the next full switch-port and phone update process is run.
To resolve this issue, you can manually run the process on the switch or on all switches.
Refer to the Manually Running the Switch-Port and Phone Update Process section of Configuring Emergency Responder.
For more details about resolving Emergency Responder, refer to these documents:
Voice applications (CRS, PA, CCM Plugins, CER, CCC, MeetingPlace, etc.)