With creationtime being a field you can find, you can push it through some pipes to find those that haven't used their accounts.
You will have to figure out the part that counts back 45 days from today, though. (That's the bold italicised part.) :-)
gam print users fields lastlogintime,creationtime query 'OrgUnitPath=/Site1/Group1' | grep ',Never,2017-05-12' | awk -F, '{print $1}' | gamx csv - fields Inactive gam update user ~Inactive suspended on | tee -a These.users.have.been.deleted.20170626-1141
I have used this with | grep ',Never,2017-05-' | to find users created "last" month and that haven't ever logged in.