This is BEST, and LEAST obvious way to get rid of the smell of cannabis.... BURNT POPCORN!
Back in high school after my parents left for work in the morning I would reek up the house and solve the problem simply by cooking popcorn, then putting it in a for a little extra time to burn it.
Burnt popcorn is very strong, and who would expect popcorn as a cover up? Febreeze, incense, and all that other shit is super obvious that you are trying to cover something up.