Originally posted by Irongate Smiffe:

You can remove the tar liquid. but you will delete other things aswell around you! The command to do it forcedelete. and you have to be at around the centre of the Tar for it to work best.

Write forcedelete 10 (for 10 meter radius) while you stand in the centre of the tar. This command removes ANYTHING that is destructable or spawnable with very few exeptions (boss stones is one exeption)

Or, and hear me out here, you can EMBRACE THE LUMP IN ALL OF ITS LUMPY GLORY. Either method works, I suppose.