Tips for further editing

Downloading the windrose chart as SVG is recommended. SVG is a terrific vector graphics format that most people don't seem to know about. What makes SVG so good is that – unlike PNG – it's very editable! You can edit text, drag individual elements around, change colors and much more with a vector editing program like Inkscape (free & open-source), Adobe Illustrator, or Sketch. What's more, as their name suggests, SVG's are scaleable.
If you know a little about SVG syntax you can open it in a text editor (like VS Code) and edit it directly.

Other options for making wind rose charts

Need even more control over your wind rose? If you're familiar with D3.js, here's a good Observable notebookto get you started.

JavaScript not your jam, but Python or R are? Check out python-windrose, a matplotlib-based library or use this R script.