Prevent OS X from seeing a disk previously used for Time Machine as a TM disk
There is a command named bypass that should allow you do remove Time Machine related files. This command should precede the rm command.

The path to the bypass command is given below.

/System/Library/Extensions/TMSafetyNet.kext/Contents/Helpers/bypass


An example is given below.

/System/Library/Extensions/TMSafetyNet.kext/Contents/Helpers/bypass rm -f /path/to/file/name


There also a service written by a third party that allows you do execute the bypass/rm commands from the Finder application. If interested, I could provide a link.