[Plugin: Watermark My Image] trying to remove watermark from my theme's thumbnails

Hello,

The plugin should skip any thumbnails, unless you have some custom ones.
See line 650 from watermark-my-image.php

Anyway, can you show me your site ?

sure, and thanks very much

have a look at the austin swivel chair here:

given what you said, they are most likely custom – it’s a great theme and has lots of features, so that makes sense ??

https://uprightdecor.com/rentals/chairs/

Yes, the thumbnails are custom, that’s why the plugin watermarks them.