Not terribly helpful volume labels.
Which is which ?
Assuming from the window style that that's XP running on C: and it kept "system" status. You should just be able to remove the W7 entry from the BCD, leaving XP as the single system and retaining your grub dual-boot (without a second menu). You can just format W7 out of existence, leaving its bootmgr behind on the XP partition to boot XP.
If you want to remove the W7 bootmgr too, you can use
EasyBCD 2.0 / Manage bootloader/ Uninstall Vista/7 bootloader, which will reinstate the XP NTLDR. But be warned, if you do so it will take over the MBR and you'll lose your ability to boot Linux until you reinstall grub to the MBR.