Christmas has passed so it's time for that yearly tradition of disposing of that tree!
Disposal specifics vary from city to city, but generally speaking you should remove all decorations and either cut the tree into pieces and dispose it in your green bin or leave it on the curb until the end of January where a sanitation crew will come by and pick it up.
Here's some more info for each specific community:
San Francisco: Recology will pick up trees left curbside between January 2nd and 16th. If your tree is over six feet tall, cut it in half. MissionLocal has the inside scoop on what exactly Recology does with all those trees (spoiler, THEY BURN).
San Mateo County: Varies from city to city, but generally Recology will pick up your tree from the curbside until the end of January. After January, you can dispose of it in the green bin. They also have a list of drop-off sites that will take your tree.
Oakland: The city will pick up your tree in the first two weeks of January. After that, your tree will be collected for free at the Davis Street Transfer Station.
Berkeley: The city will pick up any curbside trees until the end of January. Cut your tree so that it's a maximum of five feet tall. You can also drop off your tree at the Berkeley Transfer Station (1201 2nd Street) for free in the month of January. After January, you will be charged $23 at the station.
Alameda and San Leandro: Alameda County Industries will collect any curbside trees no bigger than six feet until January 23 for free.
Check your local waste management services for your community if it is not listed here. Christmas just passed so many still have yet to announce their plans.