Absolutely, I used to do just that when I had both plants in OH, also Z5. Letting frost zap the foliage makes cleanup a lot easier (and less sentimental.) Both cannas and EE's will lose foliage from a frost, but shouldn't hurt the bulbs/rhizomes, unless they are in pots and the temp is low enough, for long enough, to freeze the soil.

Take some good pics before Jack Frost arrives, to get you through winter, and just in case storage doesn't go well!

I dig up and pot Colocasias (elephant ears) shortly before the first frost, cutting off most or all foliage and moving pots indoors at the fringe of my indoor growing areas to stay semidormant over the winter. It shouldn't be a problem potting them up after a frost/light freeze.

One new (to me) variety, Pink China is staying outdoors, to be heavily mulched in hopes of seeing it again in spring (I propagated it over the summer to have an indoor insurance policy).

http://www.logees.com/elephant-ear-pink-china-colocasia-hybrid.html

they will die and come back next year dont worry about it

In Z6 that wouldn't be guaranteed.

For 2 years now, pink china stays outside for me in z6b SE mass. All I use is an inverted flower pot.