To stop the Canon IJ Network Scan utility from appearing in your menu bar, you will need to remove it from your Login items of your account. Reading your post it sounds like you got close to doing this already, but since it appears to have not worked, here are some steps.
1. Open System Preferences > Accounts and select your account. Click on Login items, highlight Canon IJ Network Scan and click the - (minus) button to remove the item from the list. This will stop the item from starting at login.
2. To now disable (remove) the Canon IJ Network Scan utility from the menu bar, either restart your Mac or open Activity Monitor, select Canon IJ Network Scan in the list and click Quit Process. Note that Kappy's method of removing the icon does not work for this utility.
HTH
PaHu