Hire a good carpet cleaner guy.
you can try spot cleaning with carpet foam cleaners but the stain is probably gonna show up again .
I've had some pretty nasty stains that I tried to rub off with elbow grease and special carpet foaming stain removing spray.
the only thing that did a big difference was hiring the carpet cleaning guy!
good luck

Any stain can be removed....you KNOW that....but at the expense of the carpet.
Chlorine bleach will remove most stains, but also will rot a carpet.
But I do know there are some things that will magically remove red wine when you thought nothing would.
Linda C

The carpet has gotta go anyway just as soon as the contractors are finished stumbling through with their dirty work boots.

I just thought it would be a good time to experiment with harsh stuff. The house was once a rental property so it has lots of different stains, many unknown, to experiment with.

I tried chlorine one one red spot and it bleached the gray carpet around it and left a red bulls eye.

Try "Spot Shot". It seems to take out any sort of stain. Also, it wouldn't hurt to try the Mr. Clean Magic Eraser.

I have a pink carpet in my family room with a big strain. My kids were playing with the "Barbie pool" indoors. Yes,it was a plastic frame that held water. Meant to be played with outside only. Well, they splashed and spilled all the water out of the pool. I did my best to blot it up, but it left a water ring about two feet across. I did everything to get the stain out, every rug shampoo, hairspray, rubbing alcohol, you name it. I had the ChemDry professional come in with his big suction machine. The water stain is gone, but so is the pink color. All the chemicals took out the pink color, leaving a round area that's a sick-looking yellow. I have a small latch-hook rug I throw over it to disguise it. I have learned that, yes, some stains don't come out.

Try Oxy Clean - got the red wine stains out of my $4k wedding gown and never damaged the fabric. Looks beautiful. Leave it sit, rub it gently and be patient.

Resolve has also worked very well for me on my rugs.

There is a cleaner called "Red Relief" that I use for red food dye. It is a reducer, chemically. That means it reacts and takes oxygen from another compound. This turns it into a yellowish stain that is easily removed.

Organic red stains (berry stains, wine stains, for example) use a sister product called "Stain Magic" that is an oxidizer. Oxy-clean works similar, with a different underyling chemical compound.

A good carpet cleaning company should know about these or similar products.

Here is a link that might be useful: Stain removal guide

That "stain removal guide" is a bit bogus. All they do is recommend their own products. For instance they say to use Rust Away to remove rust but ANY cleaner that contains oxalic acid, like Zud and others will remove rust. (Read lables!) Lots of things they sell can be substituted with cheaper alternatives, or crative use of things that you already have around the house.

Having been a manufacturers rep for a well known commercial carpet manufacturer, I can say with confidence that some stains do not come out. And the red dye stain that started this thread is not removeable without damaging the rest of the carpet. I had to go on a claim at a large casino where at least 30 rooms had this red stain, coming from some type of drink guests were returning to their rooms with. The housekeeping staff found a product called something like Red Out, and had tried using it on these spots. The red itself became a lighter shade of pink but the entire stain almost doubled in size because of them using this product. In addition, the area surrounding the spot was over saturated and the carpet color was lightened significantly.
There is nothing that could be done in this case. The carpet was ruined.
I myself spilled (accidently) some Pepto Bismal on my very expensive bedroom carpet. The pink stain is about 3 inches big. I have tried everything possible to remove the stain, but it will not lighten or come out at all.
To those parents with children, I would strongly suggest NO Hi C or any other red colored soda or juice. These stains rarely come out. Want to know the 2 other almost impossible to remove stains? French's mustard, and hot coffee.

I started the thread and as I explained a few days later the carpet was on its way to the dump anyway so I was experimenting with anything recommended. My final report is essentially the same as that of cearab.