If you’re refering to the problem with gimbals, please take a look at this thread. Please, take into the account that we’ve updated our Raspbian image!
Anyways, if you just want to try out a newer APM version, you can use our docs entry on the issue and launch APM locally, i.e. sudo ./arducopter-quad instead of launching the binary that is somewhere in the $PATH.
If you’re sure that you want to uninstall the APM altogether, then the simple sudo apt-get remove apm will do.