I have a LG LW5016 air conditioner. It is a room ac that is 5000 btu. It seems that water is building up inside of it. Is there a way I can drain it?
Usually if a window mount AC is not draining, then it is not installed properly. Typically these units need to be installed so the underside is level, or tilted so that the outside is slightly lower than the inside.
The drain hole might also be clogged, which can usually be cleared with a bit of compressed air or a pipe cleaner.
I could not easily find the manual for your unit, so I am unable to advise on the correct installation angle or the location of the drain hole. You should try to find the owners manual.
Edit: I found a copy of the manual: https://mans.io/files/viewer/808290/16#navigate_bar
The rear of the unit should be about a 1/4 inch lower than the front of the unit.
The unit also comes with a drain pipe you can install to drain the condensate faster if it doesn't drain correctly by itself. Theoretically, you could just remove the cap and not install the little pipe, but the pipe is designed to carry the water away from the metal case and reduce corrosion.
Some (if not most) air conditioners make use of the water the builds up in them to improve efficiency by slinging the water against the condenser. Some owner manuals even point this out, including the one for your model! You can download the manual from their website, but to quote:
This air conditioner is equipped with a slinger fan. (See drawing.) The fan’s outer ring picks up the condensed water from the base pan if the water level gets high enough. The water is then picked up by the fan and expelled through the condenser, making the air conditioner more efficient.
As long as no water is making its way into your dwelling, you should be fine. If the noise of the water slinging is too much for your liking, some air conditioners come with a plug of some sort on the bottom of the drain pan that you can remove to let the water out, such as this GE model AHW06LZ: