WordPress includes the ability to have an unlimited number of users. Each of the users can be assigned one of the five roles. Let's look at these roles one at a time, starting with the most powerful.
When you installed WordPress it created a user for you named admin. This, of course, is an administrator (and this first user cannot be deleted for obvious reasons). As you have already seen in the earlier chapters, administrators can do everything.
The administrator's primary purpose is to manage everything about the blog.
It is not recommended to have multiple administrators on a blog. It is best to keep just one administrator for a blog with 10 to 20 authors and editors, or perhaps up to three for a blog ...