Is the table sealed - is there a varnish finish on it? If yes then the stain is probably only on the surface and could be removed with luke warm soapy water. If not then the timber is stained and will be very difficult to remove.
I'm not sure what you can do if the table was fully sealed.
Be sure to turn the table upside down and experiment with the underneath before using anything on the top.
I'm not joking but if the table is a small one you could try staining the whole table with tea stain and finish off with a light varnish.