Hard drive keeps asking for password
There is probably an obvious fix for it but I can't seem to find it: I have previously configured time machine to encrypt a volume on my mac for backup but I stopped using it as a backup volume and would like to use it as a normal volume. However every time I boot up the iMac the hard drive asks me for a password. Is there a way to remove it?
thanks
MacBook Pro (13-inch Mid 2010), OS X Yosemite (10.10.2)