Comment 74 for bug 151544

You use system>admin>network. That way your interface is configured without network manager and it is fast. The only problem is for laptop users like me who need to switch between networks very often, network-manager is VERY much better at that.

By the way you should comment on the main bug, not in the duplicate?
To remove network manager, just find it in synaptic and remove it. You have to know how to configure your network with the other user interface afterwards however, so I suggest you practice with that first.