To delete a site detail from FileZilla's Site Manager, follow these steps:

Step 1: Open the Site Manager: Open FileZilla and go to the "File" menu. From the menu options, select "Site Manager." Alternatively, you can use the keyboard shortcut Ctrl+S.

Step 2: Select the site to delete: In the Site Manager window, locate the site entry that you want to delete from the "My Sites" list. Click on the site entry to select it.

Step 3: Delete the site: Once the site is selected, click on the "Delete" button located on the right side of the Site Manager window.

Step 4: Confirm deletion: A confirmation dialog box will appear to confirm the deletion of the site. Click on the "OK" or "Yes" button to proceed with the deletion.

Step 5: Save changes (optional): If you have made any other changes to the Site Manager, such as adding or modifying sites, you can click on the "OK" button in the Site Manager window to save all the changes. If you don't want to save any other changes, you can simply close the Site Manager.

After following these steps, the selected site detail will be removed from FileZilla's Site Manager, and you won't be able to connect to that site directly unless you add it again.

It's important to note that deleting a site from the Site Manager does not delete any files or data associated with the FTP server. It only removes the site's connection details from FileZilla.