Can you show us a picture, Tinkerbell? I'm not sure what "crowned" means, since that is not an exact term, but some people use it to mean pollarding or stubbing back, and pruning to recover from that takes a fair amount of skill, at best.

Trying to keep a large tree small is an uphill struggle and keeping an attractive shape is a real challenge. You can cut off branches as much as you like but it will still need doing every year to keep it small. It might be better in the long run to decide how much space you can spare for a tree and buy a new one that will not get any bigger than that. In a small garden there are many trees that would probably be more attractive than a pollarded willow and you could have flowers and (possibly)fruit..perhaps a crab on a dwarfing rootstock?