For the moment, access to this area by climbers should be from a temporary trailhead/parking area that is located near the old Morrell's Wall Parking Lot area. From there, the new Tom's Thumb Trail leads up toward Morrells Wall, Gardeners Wall and on to Tom's Thumb. Please look for, and use designated climber access trails.
Morrell's Wall lies in between the Sven Slab area and Gardener's Wall. It's fairly up on the side of the slope and the approach is a bit of a grunt. It seems to have fallen somewhat out of favor over the last few years, probably because of the access issues due to Arizona being up for sale to the highest bidder. There are some good routes up there that are worth the hike.
Getting There
If you drive in as for Gardeners Wall, you will see a faint track on the left before you get to that turnoff. This can be followed south to the Morrell's Wall. I'm not sure about the legality of this drive-in, so you're on your own.
The Classics
Mountain Project's determination of some of the classic, most popular, highest rated routes for Morrell's Wall:
Approach beta - once you get to the "parking area" follow the double track towards the wall. Follow the track as it turns left and seems to dead end. Continue up the slope in the same direction until you gain the left hand ridge. Follow this ridge, which has a cairned trail on it, up to the wall. We didn't do this, and headed straight up the gut towards the wall. Heinous. We discovered the correct way on the way down.