Trim off dead and leave the rest. Do not cut remaining live growth.

Maples pruned in winter tend to bleed, think of sugar maples being tapped at that time.

How the tree responds to a trunk chop will depend mostly on the vitality with which it was growing when it went dormant in the fall. A tree full of energy will respond by back-budding profusely, while one that was stressed may only send out a few new shoots.

There is no real reason NOT to undertake the reduction at this time, especially in a tree so genetically vigorous. The tree's energy reserves are finite and about the only downside is you may need to wait while cambial tissues dedifferentiate and reorganize into meristematic tissue to form new buds, but that's not going to cause much delay.

I prune/trunk chop containerized maples every year just before budswell in the spring, and though they do indeed bleed, they seem to suffer no ill effects from the practice.

Al

It was weak in the fall also. If I can already see buds, are they already swollen and it's too late?
I could always try to nurse it back to health and chop it down in the fall to try to achieve a multi-trunked tree.
Maybe that's a better time?

There is little harm in chopping a tree that is not in leaf. Most of the energy the leaves need to open initially comes from sugar/starch deposits at the base of the bud. If you do chop the trunk, energy stored in roots & cambial tissues will be channelled to those buds you might leave on the plant or toward activating latent adventitious buds.

Al

Okay, thanks. Maybe I will go ahead with it.
How many inches do I need to leave above the soil if my hope is for it to come back multi-trunked? Any?

Not much. For bonsai applications where a multi-stemmed plant is desired, the trunk is often chopped through or immediately above the basal flare.

Al

Thanks for the advice.
I'm going for it!