How do I remove the reclining lever on the side of the front seats?

Typically they're press-fit with no locking mechanism, push back on the upholstery to see if there's a splined or grooved shaft, that's the easiest way to tell.

I usually wedge an open end wrench behind things like that so you can evenly apply pressure when pulling them off and not break the edges of it.

Just to verify, you're talking about the LUMBAR lever yes since these things have power adjustable seats.