And how to add another administrator?

Created a level of membership. I want to remove. How do I?

And how to add another administrator?

1. Administration > Settings > Membership Levels.
2. You have two options:

1. Change the Role for the account from 1 to 3 in the database under the Profiles table. You must clear the cache directories after doing this.
2. Install the free Deanos Tools module, which includes this feature and more.

Thanks, I'll try.

Second question.  As a normal user to do a second site administrator?

The second point in my post concerns making another account an administrator. You have two options, as said above. Unless you mean something else...

Thank you very much.

I installed Deanos. And it works. Issue has been resolved. Thanks!)

http://www.boonex.com/m/multi-admin-access

this is the greatest tool for adding multi admins. so without giving away the farm, you can implement utilization of multiple admins for different areas of your site. 

this is a great mod. 

Deanos mods is the best for that application.  I just wish he had one for several different levels, but for what you are looking for is perfect

old post but updated info... Deanos Tools is two versions old and does not, as of this date, work on 7.3.  so... old fashion manner only, for now.