Yes you can but wait until autumn to do so and simply remove the leggy growth.

Azalea prefer full sun to light shade, so if it is leggy now it will get leggy again within a few years. So I suggest moving it to a sunnier spot.

Mine is happy with sun from about midday. It got pruned quite hard last year and it has excelled itself this spring.

I actually had to do this very thing. I had a big old azalea with spindly growth and sorry looking blooms - maybe two or three here and there. I got out the loppers and cut it back to a stump about two feet high, removing every single branch.

That was three years ago. My azalea now has a whole new top which is completely cover with buds ready to break open - double buds & triple buds. Lush green leaves and active growth will follow.

You may have to sacrifice one season of blooms, but will be nicely rewarded for your patience the following season. Keep it watered, especially mid summer.