It says “Do not submerge in water”. 
It was given to me by an coworker because they no longer use it and I will. However, since it’s pre-owned I want to wash it.
If i submerge it it soapy water then give it a few days to thoroughly dry, will it still be unsafe? Or is the warning just cautioning some dummy not to submerge in water while plugged in? Would the dishwasher be a better choice or would it still count as “submerging”?
We have an electric tea maker. It says “do not submerge in water.” If it says that, don’t do it. Obviously, don’t do it while it’s plugged in, but it seems very likely that submerging it in water will wreck something in it, possibly permanently.
But, you could try it. Obviously you got along without one, and if you wreck it you can get along without it again.
The one we have, the thing you put the water and tea in is washable, as is the teapot it ultimately runs into. Those things you can submerge, in fact you can put them in the dishwasher. Just not the motor/electrical parts.
We got ours as a gift and used it a few times. It was by no means easier than microwaving some water and making the tea that way, and while it was a very cute setup it was just too much trouble. (I actually feel the same way about rice cookers. Cooking rice is dead easy. YMMV.)
The control circuit (cuts the power when boiling) might contain components that are sensitive to being wet or that may become corroded.
Not really bothered with wrecking it. It was given because of the sheer volume of tea I drink at work,the person thought it would be nice for me to have there.
My concern was with getting a nasty shock, not destroying the device.
Is there reason to believe it has some deadly bacteria or virus? Why not just wipe it with a slightly soapy sponge followed by one with clear water? If it has scale, it can be cleaned with a solution of vinegar and water:
That would probably work for the general cleaning you want to do, too. Don’t fill it to the max because it will boil over. BTDT!
It was a nice gift, please don’t wreck it. 
I love mine.
I killed my garage remote by accidentally submerging it in water. Drying out the innards didn’t restore the circuits and I had to replace it.
Well…yeah…
This isn’t a circuit board though. Just heating water.
You can definitely submerge it in water, and after, you can still use it to make tea.
It will make a fine stirrer. Just don’t expect it to heat the water any more.
I think we need to clarify exactly what kind of ‘tea maker’ it is. Most of the ones I see online are basically a jug with a heating element - some have a stirring mechanism. My tea is made in a teapot with a teabag so I am at a loss to know why anyone needs a machine.
What sort of diseased monstrosity is your coworker that you need to clean a device that boils water? Fill it, run it, empty it. Voilà, clean!
You do realize you can wash it without immersing in water? Many electric kitchen device have the warning, but you still can clean them.
Fill it with hot, soapy water and use a sponge or brush to clean. The only part that needs cleaning for health reasons is where you put water, anyway.
If the outside needs cleaning, use a sponge.
It would help quite a bit to post a link to a page that has at least a picture of your device.
There’s just too many different things called “tea makers” to allow us to be helpful on how to clean it.
Note: I have found Magic Erasers to be quite good at removing tea/coffee stains. It seems to be the key target of their design.
One never knows for certain. You ever watch hoarders? I decline potlucks for the same reason.
Maybe I should just forget about it and move on. My OCD will always win.
You wash the inside with boiling soapy water followed by boiling vinegar.
You wash the outside with a disinfecting spray. Maybe bleach, or vinegar followed by hydrogen peroxide. This should be OCD friendly enough.
Just don’t dunk the whole thing into a bowl of water.
When I used to work at a hospital, the maintenance manager told me that he had been called to a junior doctor’s flat because the electric kettle wasn’t working. When he looked inside, it was obvious that someone had tried to heat up a curry in there and it had solidified around the element.
Maybe the OP’s co-worker likes curry?
I spent a little time as an assistant to a pinball/arcade repair man. I was amazed that one of his tricks to fix a failing circuit board was to remove it entirely from the machine and scrub the heck out of it with soap&water and a brush. Afterwords, he would rinse it clean and dry it completely for days. He claimed a fair number of problems were solved by his cleaning method.
I asked about the common knowledge of “water + electronics = bad” and his reply talked about making sure no residue remains that could short circuit the board when it finally is reconnected.