How do I remove old stains from a beige carpet?

Try Resolve carpet cleaning, for a start.

https://www.hometalk.com/search/posts?filter=clean%20carpet

Jenene....We like Blue Magic spray from Auto Zone. Works really well on old stains for us.

I use Carbona 2 in 1 oxy-powered carpet cleaner. It is in a bottle that has a sponge/brush on the top for quick clean-up of a small stain. I also use a warm solution of Oxy Clean, water and a stiff bristle brush making the solution strong. Not too many stains that won't come out with one of these. Good luck.

Resolve works well. Dollar Tree foam carpet cleaner also works well. I also buy the liquid in the spray, treat it first with this for 10 mins., then put the foam on, use a carpet brush to scrub it out, and then I run my carpet cleaner over the whole thing. I buy this stuff by the case at Dollar Tree cause I am a caregiver to the disabled. I've gotten out stains that professional cleaning companies didn't get out.