Failed to delete link, yellow triangle is displayed.

Question

I am working on a project and there is a yellow triangle on the FSharp.Core link, so I decided to remove this link and add it again.

But when I right-click on this link, there is no way to delete the link. I also tried deleting it using the delete button, but that didn't work either.

But all other links work fine. I can delete or add them.

I have no idea why this is happening. Can anyone help me with this?