Can I change/edit this?

Yes. All templates provided are editable. Having said that, there are some elements like watercolor splashes, doodles, frames, handwritten designs, etc that typically cannot be edited in PowerPoint. This is because we often employ styles and methods that aren't fully supported in PowerPoint. In order to preserve the design, we have to flatten the file which makes them un-editable. Usually, the most flexible file format is Photoshop, Illustrator, or SVG because you have more options to manipulate each layer.