Is there a way to rotate the image?
I usually just edit the image that's embedded into the note.
On windows it's pretty easy by opening the photo and then doing your edits.
On linux, I usually just open an image editor or rotate the photo in a viewer and save over.
I thought it was that easy, too, but got a surprise when I viewed the note on another device (mobile).
I'm still using the latest stable release for desktop, which, as of this writing, is 2.6.10. The modified resources (cropped, rotated, annotated, whatever) show up for you on the computer where you made the edits, but those edits don't synchronize to other devices. In your situation, this might be OK, but still something to be aware of.
The feature requested in issue #279—allow editing resources outside Joplin—didn't get implemented until somewhere around v2.7.12, a pre-release.