alright man this is what I did, log in, press [esc], got to video settings, change your chunks loaded to 2 and your max fps to 10, lower all your other video settings as well and set it to fast. Now close your game out, open it up again, and break that pesky farm manager as quickly as you can (not if there are upgrades they will likely be gone, so feel free to try and snag them out first). If you put a range upgrade in it, don't do that until the next patch of the game comes through.
Alt way would be to remove it using MCeddit.