"It was not difficult to find your profile."
Translation:Det var ikke vanskelig å finne profilen din.
Actually, "deres profiler" would be "your (plural) profiles (plural)". As in the profiles of you and your friends. So this would mean something else.
You could however say "Deres profil" (yes, the capitalized 'D' is intentional and makes a polite (and very old fashioned) way to say your (singular)), but this would sound very weird to a Norwegian, and they would think you are from the past.
Does it ever appear in contemporary Norwegian, in formal correspondence maybe, or has it now completely disappeared?
In formal settings you would say "Deres Majestet"(Your Majesty) if you were addressing a royal, but if you met them in any other circumstances you would say 'du'.(If that were to ever happen)
'De' could be used sarcastically if you were talking to a person who was acting pretentiously.
So I'd say it has "completely disappeared".