Ready for New Year #5: remove carpet stain

I don’t want to do this anymore. The carpet was a very cute headboard substitute but now I moved my bed so it’s in a weird place and also what even is this stain. Stain remover (mine is soda ash based) is harsh on wool so that’s a last resort. Also once I wet it I won’t be able to see if the stain is gone. 

Okay I am just going to wet a rag and grab the citric acid so I don’t have to make two trips if the water isn’t enough. (Vinegar would do the job the same way but I find it easier to keep citric acid on hand; our vinegar is always used up)