@Jenny Keffer It really depends on your Management Agreement and what the terms of it are. I would say typically they run for a year and then continue in perpetuity renewing each year on the anniversary. Likely there is also a clause for early termination which would penalize the owner for breaking the contract.
Now, if they have been negligent this should be pretty easy for you to break from them. Especially if they receive correspondence from an attorney. First, you can try to just tell them due to what you feel is them breaking the terms of the contract you no longer need their services. You should request something in writing confirming this, and they will not seek to enforce any sort of "early termination penalty".
You also need to get your statement for 2015, hopefully they will provide that for you, so that you can use the information contained therein to file your taxes.
Finally, make sure you get the security deposit, as the company should be holding that money as well.