You can clear the phone only if you have local access and as you told before you don't have that so you'll have to load a 46xxsettings.txt file in the phone unlocking the local access and delete any local access passwords.
Try this :
Use a switch with a monitor port, connect you laptop to it and run wireshark, monitor the port were you connect your phone on
Boot up the phone and find the HTTP server it is looking for ( IP Address )
Then give your PC that address and run a HTTP Server like Avaya's MV_IPTel and make sure the 46xxsettings.txt form the IP Office is in the root folder of the HTTP server
If done so rebbot the phone, It will fetch the settings file ( visible in the display ) and at a given time the phone will "hang" waiting for something to happen, doesn't matter what. Reboor the phone again and at a certain point it should show "press * to program" then press * and it will ask for a password completed with a #, the password is either nothing ( just press # ) or is is 27238.
If none of the above happens and the phone reboot after entering the password then you'll have to edit the 46xxsettings.txt file and set the local access parameters to default or known values.
If you get access the scroll to Clear phone and confirm with # twice.
This part has to be changed in 46xxsettings.txt
############# LOCAL PROCEDURE ACCESS SETTINGS ############
##
## Restrict Local Procedure Access
## Controls whether local (dial pad) procedures can be
## used to administer the telephone.
## 0 means local procedures can be accessed from the
## telephone.
## 1 means local procedures can not be accessed from the
## telephone.
## CAUTION:Be absolutely sure before setting PROCSTAT to 1
## SET PROCSTAT 0<< erase ##
##
## Local Procedure Password
## Sets password for local (dial pad) procedure access.
## (1 to 7 ASCII numeric digits). See your telephone's
## Administrator's guide for the default password
## supported by your release.
## SET PROCPSWD 9999 << erase ## , password remains 9999
##
#################### LOGIN SETTINGS ######################
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