You have 2 options as the keyboard isnt easily removable.
One is to remove the key caps and and clean underneath them.
Two is to use compressed air to clean underneath the keys.
If 2 doesnt work 1 is the way to go.
WHEN REMOVING THE CAPS, BE CAREFUL NOT TO APPLY TOO MUCH PRESSURE AS YOU WILL BREAK EITHER THE CAP OR THE MECHANISM INSIDE!
Hope this helps as this was the 4th or 5th time of me writing this. If it did please hit the accept answer button!