On of the best tools at your disposable in Corel PHOTO-PAINT is the Clone tool. This tool helps you to remove areas of your photo that you wish to remove. It allows you to take pixels of surrounding areas and cover up the unwanted portions. 

In this example I needed to remove the photo-bomber from a picture of myself and my son. I used the grassy areas to covered her up!

Scroll down to watch the video.

Clone Tool in Corel Photo-Paint