To remove unwanted parts from an image, select the image and then choose the
option

You need to make use of the Brush tool for removing the unwanted part of an image.

Explanation:

Yes, it is the brush tool or the lasso tool that you can make use of. and you will find brush tools in all sorts of image processing software may it be the paint or Photoshop. It is common to both the raster-based and vector-based image processing software. And you can easily find it inside the tool section, and then make use of it to remove the unwanted parts from an image.