You can run regedit without administrative privileges by launching it as a non-administrator. If you launch it as an administrator user, you get the UAC prompt, but if you launch it as a regular user, you get no prompt and most things outside of HKEY_CURRENT_USER are read-only.
regedit.exe is marked with <requestedExecutionLevel level="highestAvailable" uiAccess="false" />
, which does not always ask for admin permissions, only if the current user is an administrator.
If you really need to run regedit as an admin user without admin rights, according to this thread, you can use the Compatibility Administrator tool to configure your system to ignore the requestedExecutionLevel
.