Can we limit the bandwidth usage in cpanel? not in WHM but cpanel or is there any way to limit diskspace too, just like in WHM? thanks in advance
i think there was some 3rd party apache module that could limit bandwidth usage per cleint IP. not sure if this is what you are looking for.
You need to create separate cpanel account to the sub domain. You can't do it from the cpanel interface.
There is no way to do this from cPanel itself. You'd need to either create a new account for that domain, or you'd need to have root access to the server to recompile Apache with certain modules which would limit bandwidth, then add some details in an Apache include file.