How to Enable Share-point Designer in Central Admin

Below are steps for SharePoint Designer settings in Central Admin:

1. Open Central Application Website.
2. Open SharePoint Designer Settings under General Application Settings.
3. Select your web application from the drop down at the top of the form.
4. Select the appropriate options as mentioned below(per your needs) and click  ok.

There are four check boxes as listed below:

Enable SharePoint Designer : This Enables or disables SharePoint Designer for the Web Application and all of its site collections.

Note: If unchecked, users still see SharePoint Designer buttons in the browser, but when they click them, they get a message stating that SharePoint Designer is not allowed on the site.

Enable Detaching Pages from the Site Definition : This option enables or disables the ability to detach pages from the site definition. If unchecked, SharePoint Designer only allows you to edit pages in normal mode. The Edit File in Advanced Mode is disabled. Running in Advanced mode lets a user ghost pages by modifying them from the content originally in the site definition stored on the server’s hard drive. The customized version of the page is stored in the SharePoint content database. Any changes made to the site definition files aren’t reflected in detached pages. This can create maintainability problems and should be used with care.

Note: This setting does not apply to pages that have already been detached as well as new blank ASPX or HTML pages created by the user.

Enable Customizing Master Pages and Layout Pages : This enables or disables the ability to customize master pages and page layouts. If unchecked, SharePoint Designer does not display Master Pages or Page Layouts in the Navigation pane.

Note: Page layouts also require publishing enabled on the server, so if you have enabled it here but the site is not a publishing site, you will still not see the Page Layouts option in the Navigation pane.

Enable Managing of the Web Site URL Structure: This enables or disables the ability to view and edit files in the URL structure of a site. If unchecked, SharePoint Designer does not display the All Files option in the Navigation pane.

Note: These four options are also available at site collection settings.