I wouldn't prune these in February in your zone - if you stimulate new growth and have a later hard freeze your plants could be damaged. During or immediately after bloom is better timing.

And while you can cut them back that hard, a healthy azalea that is 7' now will eventually reach that same size again - you won't permanently reduce its height by hard pruning. You can always prune again later, but an ideal long term plan would be move them and replace them with something that fits your site.

Morz8 gave good advice. Here is an additional concern:

Severe pruning of azaleas and rhododendrons is common. However, Tyler Arboretum, just west of Philadelpia, found that the plants must have some sun for this to work. Plants that they severely cut back in deep shade frequently died. Sometimes the reason that a plant is tall and spindly is that it doesn't have enough sun. If that is your case, it would be best to open up the shade a little now and then prune back after they bloom in the spring.

Opening up shade can mean several things:

Moving the plant to a site with partial shade, and more sun,
Pruning back plants that are casting shade,
Pruning off the lower branches of trees to give "high shade".

Here is a link that might be useful: How to grow azaleas.