How to remove left over uncategorized metafield from app"

[sagetrails]

I used a workaround to give customers a field to type in the color they want for the product with the app https://options.ymq.cool/.

Now I want to use the shopify metafields, which don't seem to work. I de-installed the ymq-app but there seems to be something left over so the shopify metafields don't work. 

I use the lasted version of the Craft theme, in case that's relevant.

How do I get rid of these? 



Thanks in advance.