Can I install the Android M Developer Preview on HTC One?
The M Preview images are for nexuses only so it wont work on any other device, although if you really wanted to try out Android M there is a possibility that a developer somewhere takes interest in developing one for your phone as soon as source code is released but you will have to wait though. You should be able to remove the ROM from MultiROM but its always advisable to take a backup when changing ROMs.