Servers does not have adminn mode, only client.
Server users accounts, to every account assinged various access rights.
By default, there are "Full" and "Operator" user groups.
And two accounts - "Administrator" ("Full" group) and Operator1 ("Operators" group).
At server startup, press "Staff" button :
[attachment=40:attachment]
Then choose your account and press "Settings" button. Password will be requested, enter main password (111 by default).
[attachment=41:attachment]
Now you have account groups list (left) and access right list (right).
[attachment=42:attachment]
1. If you select new group and press "Close" button, the selected user's group will be changed.
2. If you select new rights and press "Close" button, the selected account's rights will be changed.