To access the inpaint tool, double click the image you want to edit. From there, select "inpaint" on the right sidebar. This will prompt you to draw on your image, and in this case, draw over the unwanted image.
In your prompt, state that you would like the object removed, and then click "Generate." A new image will generate in a moment!
While this is a great way to make quick fixes to your images, more significant changes (like multiple objects, colors, text, etc.) might be best corrected using "Prompt edit" in the lighbox, just a few clicks above the inpaint tool.