There are two things to release: The PARK gear is operated electrically on all model year LEAFs and must be released to allow the front wheels to turn. Read the Roadside Assistance Manual (available for download from Nissan Publications). The parking brake (if applied) secures the rear wheels. On vehicles with the foot pedal parking brake, it can easily be released with the mechanical release lever. There is a procedure in the manual to release the electric parking brake (all 2011 and 2012 models and some 2018 and later models). Since I don't know the legitimacy of the original post, I will not list the exact procedure--read the owner manual.
I had (have) no problems with the electric parking brakes on 2011 and 2019, but the 2015 with mechanical parking brake pedal required frequent adjustment of the cable or pedal mechanism.
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015; traded 8/10/2019 at 82,436 miles
White LEAF 2019 SL Plus purchased 8/10/2019