Make sure there are no references for the hardware interface while deleting.
However, share the error you are getting while deleting the interface.
port 1: MGMT (out of band)
port 2 and 3: 802.3AD aggregate/Port-Channel to switch
the port-channel interface (ports 2 and 3) will be my "inside" interface with a private layer 3 IP.
The above scenario is possible.