Standing water in front loader how to fix - Whirlpool Duet GHW9150P Front Load Washer

More details about where, when, how (and how much), etc., might be useful.
I'd check easy things like the drain hose, to make sure it's not clogged. But the most likely thing is that the filter cup has gotten clogged or the drain pump is dead.

To check out: Get a wet/dry shop vac. Hook it up to the drain hose to suck the water out of the machine and save a lot of mess.
Remove the bottom front panel. The drain pump on my Duet is front center bottom... easy to get to. There's a plastic handle to unscrew if I recall correctly, which brings out a sort of plastic cup filter. You might find enough change to buy yourself a cup of coffee. Clean it out. If it wasn't really clogged up, the problem is either something stuck in a hose, or a failing/failed pump. Check the hoses first; if it's not them, I'd order a new pump.

Remove the front panel , 3 torx screws on bottom front , open the large white valve to clean an inspect , it will have some water in it , uplug an catch what u can.

Check hose and clean hose for possible lint build up. When you remove the lint it should drain faster. this happens when you wash alot of towels and bedspreads.

You do not say how much standing water is left in the machine. It is usual for there to be some standing water in front loader washing machines. That's why if you close the front door they start to smell.
After you have used the machine you should wipe dry the door and rubber seal, to prevent residue build up. Then push the door to, do not close tightly. This allows the water inside to evaporate and escape, and you will not need to use the front loading washing cleaner to get rid of the smell. from the machine. If the door is closed tightly the water remains trapped ion the machine.