Help using functions in PowerApps

Hello,

I am new to PowerApps and not a strong Excel user just yet. I am using the employee directory template PowerApps provides. We have O365 profiles with the first name "admin" that I do not want to return in people's search. How would I change the formula below to exclude those results?

fx= If(!IsEmpty(SearchUser), Sort(Filter(Office365Users.SearchUser({searchTerm:First(SearchUser).Value}), Len(GivenName) > 0), GivenName, Ascending))

Thank you for your help!