eseid= new List<id>();//To store list of users id that is following by current user
for(EntitySubscriptionese:[select parentid from entitysubscription where subscriberId=:userinfo.getUserid()]) //return list of users that is followed by current user
{
followId.add(ese.parentid);// Parentid is id of users i.e followed by current user
                  }
userSel = [select id from user where id <>: eseid];// This query will return users i.e. not following by current user

for (User UnSelectUsers:selectedUsers){
EntitySubscription follow = new EntitySubscription ();
follow.parentId = UnSelectUsers.id;// Add the id of user (Parentid) whom you want to follow
follow.subscriberid = UserInfo.getUserId();//Subscriberid is store id of user who is going to follow
UsersToInsert.add(follow);// Add all selected user in a list
   }
Database.insert(UsersToInsert );// Insert all records from list

public List<cEntitySubscription>getEntitySubscriptions() 
{
if(EntitySubscriptionList == null) 
{
EntitySubscriptionList = new List<cEntitySubscription>();
            String userSObjectPrefix=  User.sObjectType.getDescribe().getKeyPrefix();// To get user object prefix
for(EntitySubscription c: [select id, parentid, subscriberid, parent.name  from EntitySubscription where subscriberid =:uid order by Parentid])//This query will give list of user's and records following by logged In user
 {
if( ('' + c.parentid).substring(0,3) == userSObjectPrefix) // users only, by this you can eliminate records
                              {
EntitySubscriptionList.add(new cEntitySubscription(c));// Add user in EntitySubscriptionList
                               }
            }
        }
returnEntitySubscriptionList;
    }

selectedEntitySubscriptions = new List<EntitySubscription>();
// this list store records selected by user for unfollow

for(cEntitySubscriptioncCon: getEntitySubscriptions()) {
// getEntitySubscriptions() store list of following by current user, for more info see point 1

if(cCon.selected == true) {
// If users is selected then add in list

selectedEntitySubscriptions.add(cCon.con);
}}
delete selectedEntitySubscriptions;
//once you have list of user that are Logged in  and if the user want to unfollow, use delete command and delete list.

selectedEntitySubscriptions = new List<EntitySubscription>();

for(cEntitySubscriptioncCon: getEntitySubscriptions()) {// Add list ofuser following by current use rin a list

selectedEntitySubscriptions.add(cCon.con);     
}
delete selectedEntitySubscriptions; //once you have list of user that are Logged in user want to unfollow, use delete command and delete list.