Door to common toilet from service yard?

[Babyalien 0]

hi, 

I am looking to hack away the wall between my service yard and common toilet so that the access to the toilet from the back instead of the corridor along the rooms. 

Based on floor plan, that wall is hackable but a quick check with my usual contractor says it's not possible. See image, it's the wall behind the sink. 

 

Anyone has experience doing this before? Or is there a way around it? 

Edited February 7, 2018 by Babyalien
I don't know how it ended up as multiple posting. Need to delete. Sorry.

[Gingerman 2]

Any pictures?

[dexufto 5]

Did you seek a second opinion?