Tenant putting garbage in hallway

[Sami Gren]

I have a multi family building with several tenants per floor and one tenant put out by the door their garbage Foods pizza box, and neighbors are complaining about the smell. 

Also the super has told me to tell them about it, but he hasn't cleaned it up.

I have 2 questions 

1) how would you deal with the tenant.

2) can I tell the super to clean it up regardless?  (He is responsible for cleaning building )

[Matthew Paul]

Tell the super to use his master key , open the tenants door and set the trash back in their unit .