To change the document root directory in Plesk, follow these steps:
1. Firstly, log in to Plesk.
2. Secondly, click Websites & Domains in the left sidebar.
3. Then, locate the domain you want to edit, and click Hosting Setting.
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4. In the Document root text box, type the file you want to use for the new document root directory.
5. Lastly, click OK. Plesk will change the document root directory.