Replace Recovery HD with a “bootable drive” formatted partition?
If you've installed Yosemite it will automatically have created an invisible recovery partition and so you may as well delete the recovery partition you created. Keeping a copy of the Yosemite installer on a USB stick is definitely a good idea though in case your drive ever dies or you need to perform a clean install (on an SSD for example).

Alternatively, you can hide volumes/partitions using the Utilities>Visibility function in Onyx.