There's a latch/clip located near the second window from the right.
So in your case, try pushing between the last and second to last window, close to where the T and H are. That should pop it off on one side, and then the other side should be easy.
You can see the location in the manual: https://largescaletraindatabase.s3.eu-west-1.amazonaws.com/pdf/piko_g/manual/38601_m.pdf