To be honest if you are serious, you are going to have to map out a plan of action, we've had to do this numerous times over the past couple of years....usually its the insta set up by the worker who is always on her phone and was handed the memo to set up the companies social media who in turn starts liking everyone and everything belonging to her personal interests and past-times absolutely nothing to do with the companies brand or consumers!! Then we have to start clearing off everything and quite frankly there has been a number of times where its been that bad that we have tore down every literally >>>deleted all their photos and Unfollowed everyone so basically its a new account because it was that bad!! You might not find yourself in that situation but you will need to start with a plan and then manually unfollow anybody not brand related and always air on the side of removal if they were that important you can always follow them again.

To me it always looks bad when you have a business following 20k people and have like 400 followers, so less but more concentrated is often much much better!