There are a few mods that just outright eliminate one specific Blight, but none that eliminate all.

However, there is a simpler solution.

If you are modding, you definitely have Basemod. Check your mod config how to bring up console.

Using console commands, you can just remove or add blights.

https://alexdriedger.github.io/SlayTheSpireModding/docs/console

Dont see the command for blights, but just start typing away, the console helpfully shows if the command is valid while typing.