Instagram has introduced a new feature named Mute. This allows the users to mute the accounts without unfollowing them. If you have selected mute for a account, post and stories will be hidden.
This can be done heading to Options (…) menu in the corner of a post. From there you will be able to mute post or both post and stories from the account.
You can also mute posts and stories by pressing and holding on a story in your tray, or from a profile. Update for the Mute feature will be rolling out to users over the coming weeks.