MacBook Pro 2016: Keyboard key stuck – how to remove key?
Yes, it is possible to remove the keys safely and clean them.

But first, it is important to know how it looks below the keycap in order to not damage anything:


The key cap is attached to the mechanism by two claws and two hooks. the hooks (left side of the image) are at the bottom of the cap and they would break if you lever up the cap from there. The top side is held by claws (right side of the image) which can be unclipped.





The butterfly mechanism has a round surface on both sides that touch the whole button cap. That is where the problem comes from: since there is a big contact area it can stick together easily (fluids) or become clogged. I actually spilled whine into my keyboard and many keys were affected, but I did not break a single one doing it as follows. You will have to lever the top side of this mechanism up, gently, to unattach the keycap.




So, just be careful and do exactly as described below!  


First, take a thin tool (a needle works fine, but I guess a thin plastic tool is better), squeeze it into the gap above the key and gently lever it up, until you can reach below the rim of the cap with a second tool or your fingernail. 
The first tool will likely be under the butterfly hinge which is why you have to release that one and make sure you are only just under the cap with the second one (short fingernail is the safest option). Now lever up (with the second one/your fingernail!) until it pops of with a slight clicking sound.
Now you have to untangle the hooks at the bottom side. Hold up the top side just a bit and very gently wiggle the key around, left right up down, until it is loose. Do this really gently! It should not make a clicking sound or anything since it isn't really attached to the hinge!
I mostly just cleaned the top side of the hinges with my finger or a soft cloth, but you can reach underneath the hinges, if necessary, with a fine brush.
To reattach the keycap, slide the hooks underneath the cap back into place from bottom to top. Then press the key (slightly upwards, that is in the direction of the screen, so that the hooks stay in place) until the top clips back in again.


There you go.