The thesis theme comes with a footer link like this “Get smart with thesis wordpress theme form DIY themes” .You can remove it easily by following the steps mentioned below
How to remove the thesis footer link :
Step1: Go to Thesis 2 Skin Editor and click on HTML home page button.

Step2: Scroll down to the Footer section and click on expand icon which in on the right corner of the footer section box.

Step3: To remove the Thesis attribution box we need to drag the box by clicking shift button and put it on the drag boxes here to remove them from the page.
Step4: To remove the WP admin link box we need to drag the box by clicking shift button and put it on the drag boxes here to remove them from the page.

Step4: After you finish this, you can click the green “Save Template” button to make the changes live on your site.

Update :
For thesis 2.0 read : Remove thesis attribution link from footer in Thesis 2

Note:
One should have a thesis developer version in order to remove the diythemes.com link in footer of your site.
Here are a few steps to follow to remove or hide the attribution link
1.Login and choose thesis option
2.In thesis options choose custom file editor and choose custom Custom_funtion.php file to edit
3.Or use an ftp software like filezilla to edit the launch.php file and paste and below code into it..
/* Remove footer link*/ remove_action('thesis_hook_footer', 'thesis_attribution');
4.Now the custom thesis footer link “Get smart with thesis wordpress theme from DIY themes” is removed.
Add site’s link instead of thesis footer link:
Same like removing the thesis link using a developer version you can also add your own attribution links to the footer of this theme .
You can also take a look at how to add a three column widgetized footer to thesis theme
1.Login to wp admin
2.Go to thesis options and choose the custom file editor and paste the code in the Custom_funtions.php
3.Or use an ftp software to edit the file and paste the below code in
public_html/wp-content/themes/thesis_18/lib/functions/launch.php
/* Add your own footer link*/ add_action('thesis_hook_footer', 'custom_footer'); function custom_footer() { ?> <p>Copyright © 2009 <a href="<?php bloginfo('https://mytechshout.com'); ?>"><?php bloginfo('Mytechshout'); ?></a>. All rights reserved.</p><br/> <?php }
4.Then replace mytechshout.com with your site’s name.
5.You can add your own links like contact us using this method
I hope you all must have enjoyed the tutorial on how to add or remove a footer attribution in your theme.Do also read Thesis theme 2.0 Release date
If you have trouble doing this ,post a comment i will help you through the process.Also share your experience about this post with us in comments:-)
very useful info. Works fine for me. very good.