1. Login into Plesk Panel.

2. Select the "WordPress" tab at the left side of the screen as marked in the image.

3. Click on the "Plugins" button as marked in the image.

4. Select the plugin as marked in the image.

5. Select the "Remove" button as marked in the image.

6. Select on the "Yes" button as marked in the image.

7. The plugin has removed from instance as marked in the image.
