Instagram Verfication -> Claim Username

one of my friends owns a big instagram page who is verified almost 1M (ALL legit etc)

I have an username account which he wants to change it to his.

for example

he has the account : MicrosoftBA
and he wants claim username : MicrosoftBB (which i have access to it)

But when he tries to change username it appears a red line it says please contact instagram support. even though we dont know how to contact it.

Is there any way we can do a trademark on the username? And how we can get a…

Instagram Verfication -> Claim Username