Query unknown user on Technicolor TG582n FTTC router

[#1]

I am a new Plusnet user with fibre broadband. When I first set up my Technicolor TG582n router, I recall seeing only one 'user' on the User Management page, namely - Username: admin / Privileges : Administrator / Default user: Yes.
Later, I noticed a second 'user', namely - Username: Diagnostics / Privileges: Intercept / Default User: Yes (this has replaced admin as the default user).
I have queried this with Plusnet who advised they do not support advanced features of the router but suggested a factory re-set. I carried out a factory re-set but the second 'user' still appears. All of the pictures of the User Management page that I have seen show only the one 'user' - admin.
Does anyone know if this second 'user' is normal, please, or should I delete it?

[#2]

I have a TG582n adsl and there isn't a second user so perhaps it has something to do with it being a fibre router

[#3]

Hi there,
I believe that user's included in the firmware by the manufacturers, but you should be fine to remove it if you wish - if that does lead to any issues then factory resetting the router will restore everything You won't get anyone logging in with that username though, but if you're concerned you can change the password for that user which would be another way of doing the same thing.
Hope that helps.

[#4]

From memory sometime ago it was mention the Username: Diagnostics is the username the router uses for the landing page on newer firmwares..

[#5]

My sincere thanks to everyone who took the time and trouble to respond to my query. On balance, it seems the second 'user' is harmless and probably beneficial. My inclination is to leave it unless anyone else knows differently?

[#6]

You'll be perfectly fine to leave it if you wish