Branding The WordPress Admin
While it may be cool to have the WordPress branding on a personal site there are times you do not want to see the “Powered By” text or WordPress logo, especially in the admin area. If you create sites for clients and for whatever reason don’t want them to know the site is a WordPress installation these have to go.
There are several ways to accomplish this task. This video takes a look at one method of doing that. To find out more options check after the video.
How to Remove WordPress Branding Like A Pro http://www.wordpressguideforbeginners.com/
There are several plugins that will at least partially take care of this for you. Some work better and are more effective than others. My personal favorite is called “WordPress Hacks” and the plugin is a free one. You can get rid of or change all the default text in the admin area plus change the Icon that appears on the upper left. The plugin has several other additional features that are very useful as well.