Hello kevin-tsai,   You cannot edit or disable the admin account. You are prompted to change the admin password on initial install.    USERNAME: Along with the users you created, OpenManage Enterprise displays the following default user roles that cannot be edited or deleted: admin, system, and root. However, you can edit the login credentials by selecting the default username and clicking Edit. Page : page 163 [URL]  
How to close the admin account of openmanage
close the admin account