I didn't remove the left, but I've removed the right. As I recall, I had to pull the velcro attached areas really hard to get them off. Also, I think you have to slide the panel forward. Follow the instructions in the owners manual. Good luck.
First take the seat off and separate the black plastic panel at the lower rear that extends under the seat. There is a small amount of connection that needs to be undone by taking the screw out of the black part and breaking the connection. Then take the screws out of the colored plastic side piece. That piece has some interlocking plastic pads inside that have to be separated by pulling the top away from the tank enough to break the connection and then the entire piece is free to be eased to the rear and off. It is a fiddly job and I said some bad words out loud when I first did it. It sometimes feels like a near thing between breaking connections and breaking plastic.
I did that too, and followed the good advice of Greyghost and others.
I also found the description in the owner's manual very helpful. It shows where the velco is and what direction you have to pull/push to get it released from the hooks and velco (kind of like a 10:00 direction if you're removing the right or 2:00 if the left).