No...the requirement for Happiness remains the same
consider something like the "Junkyard" it has minus 500 happiness. so WHEN you delete it, what happens ?
your happiness increases by 500, in other words you GAIN 500 happiness...
Deleting a certain building DOES affect population - < this DOES contribute to an EVENT QUEST
Deleting a certain building DOES affect happiness - < this DOES NOT contribute to an EVENT QUEST