While staining some wood, we had an emergency and had to leave. The stain has now dried and I'm not sure how to remove the excess; it's normally wiped off before it dries.
When I get home I'm going to try to brush on some mineral spirits to loosen it up and wait about 30 minutes before trying to wipe off the excess.
Any other suggestions are appreciated.
The Minwax website says to apply another coat of stain on top of that and then once it softens
up the dried stain just wipe it off like you normally would. I'm currently having the exact same problem. But I think this makes sense so thats what I'm going to try.
If the wood feels smooth to the touch and you're happy with the color then I wouldn't worry about it. Some woods absorb extra stain without a problem.
If you want a lighter stain, you'll need wood bleach. Wood bleach is an iffy proposition, but your odds are good since you don't need to get it all the way back to the original shade and the stain isn't that old. I'm assuming in this answer you used a pigment-based stain (most are).
If not, get some two part A/B wood bleach. 
(source: willyvanhoutte.be)
This is a two part preoxide based bleach (NaOH and H2O2).
Put on gloves, goggles, respirator.
Apply the A chemical with a brush. The wood will probably look darker since it's wet. Don't worry about it.
Let sit 10 minutes (follow the instructions).
Apply the B chemical. Wait about 4 hours (follow the instructions). The piece should lighten as it dries.
Wash the piece well with vinegar and water (50-50) to stop the reaction.
Leave to dry overnight.
You can repeat the bleaching if desired.
You'll have to refinish the piece as the grain will be lifted by all the chemicals. Sand normally (Start with 120, finish with 220 or as desired).
After the bleaching the wood is probably a different color than when you started. If this is one piece out of many matching pieces, my experience is that the same original stain won't look quite right (It looks unnatural, has less range and depth of color) It may be better in the long run to start over.
I didn't wipe the excess stain from my floors when I stained them. We made the amateur mistake of thinking we could just kind of wipe and blend and that it would all soak in eventually. It will never dry if you leave it like that. It's way easier to fix than people online are saying. You don't have to scrub with steel wool or anything.
Just get a flat pad on a stick with a good sponge or cloth on there, and put some standard mineral spirits in a paint tray. Dip the pad in and rub it on the floor with some pressure to loosen the excess stain. Then take clean, dry, lint-free rags and wipe the excess up. You don't have to "keep wiping until the rag is clean" just get all the excess up that you can. It comes off really easily. Then let the floor dry overnight so the stain that was under there can dry properly like it should have. Then throw down your polyurethane! I used Minwax oil-based stain, and Minwax oil-based super fast drying polyurethane for floors. (...I wouldn't recommend using a water-based poly over an oil based stain if you've done it like this.) My floors are now dry as a bone 24 hours after my last coat of poly and they look great :)
If the mineral spirits don't work out, two options would be to strip the piece, or to sand off the finish.
Stripping is always messy, but it would be easy going on a freshly applied finish. You would then have to re-sand for the new stain. I prefer the methylene chloride strippers. If you use one of them, read and follow the precautions on the label.
Going right to sanding would also work because stain doesn't really penetrate very far at all in the wood. However, you would have to allow the stain dry completely before sanding or you will gum up your sandpaper quickly. If you put the stain on really thick this may take a while and make the stripping option more appealing.
The size and shape of the piece of furniture would also be something to consider when deciding which of these would be easiest.
Use a natural colour of stain on top of the previous one and scrub with a paintbrush to loosen the old stain. Then rub off the excess. No darker colours added and it works. Just like in the olden days when women had no nail polish remover, just repaint the nails and soften the old stuff and take it all off together.
I have found that if you cannot get all the stain off before it starts to set, brush some more of the gel stain on and start the removal process. The stain that was drying will come right off. It is amazing to work with this product. I am still in the process of doing my kitchen but am addicted :). BTW.. I am using Minwax.
The Minwax gel stain did help pick up the excess of the undercoat. One thing to note is that gel stain recommends more drying time between coats. I applied with a cloth and rubbed.
