The short answer is no. Do not unfollow anybody you are following on Instagram because it will reduce your follower count.
If you look at this historical chart from IconoSquare, you can see that anytime I did a mass unfollow of “Followings who don’t follow back,” there was a huge unfollowing back of those who followed me or those I had reciprocal follows with.
The key take away is that you should be really careful about who you follow. If you do unfollow a large group of people, 25 or more, there is a ripple effect to people that are your reciprocal followers!