Did you correctly install it from booted installer so that the new install sees itself as C when booted?
Then if you post back a maximized Disk Mgmt drive map and listings screenshot, I will help you remove the old install after you copy over all of your files. Use Snipping Tool
Otherwise you can wipe the HD using Diskpart Clean Command
to be sure boot code residing on the old partition doesn't interfere, then Clean Reinstall - Factory OEM Windows 7