Clearly that edge is required to support the face below it so no, it can’t be erased. You could hide it with Shift+Eraser. What’s going on above it, though, with the zero thickness surface?
A bit of advice, wait until your geometry is correct before you start applying textures. The textures can mask problems with the geometry.
Also make sure you are using components correctly.
What are you modeling? Can you share the .skp file? Upload it to Drop Box and share the link.
Or give the top of the wall some additional thickness so you don’t have that face at the top.
Note the exposed blue back faces. It’s a good idea to reverse those before applying materials.
FWIW I fixed some icorrect tag usage which might have come in with components from the 3D Warehouse.
And I purged unused stuff from your model. File size reduced by about 54%.
Here’s the cleaned up file. I reversed the incorrect faces on your walls but didn’t edit any of the imported components. Bathroom Remodel purged.skp (8.1 MB)
Keep in mind if you try components from the 3D Warehouse but later delete them, they remain “in model” along with any materials they bring along. You need to purge unused components and then unused materials from the In Model components and materials to really eliminate them.