EasyBCD is just a utility program installed on your OS. It's not the boot manager. It's not a part of the system. You can uninstall it at any time, just like any other app on your system using
Control Panel / Programs and Features / Uninstall.
Why do you want to format C\: ?
If you want to get rid of Vista and replace it with Ubuntu, that's got nothing to do with EasyBCD.
Just Install Ubuntu, and when it wants to know where, tell it to replace the entire HDD.
But be absolutely sure that's what you really want to do first
You paid a fair bit of the cost of your PC for the Vista software included. It would be wise to protect that investment by making OEM backup/recovery disks first in case you change your mind.
Why don't you tell us exactly what you're trying to do.
I'm reluctant to advise you with so little information about what you really want.