You can view and delete likes on other people’s Instagram posts from Your activity settings. If someone has deleted a post you previously liked, you won’t be able to see it.
To remove your likes from multiple posts:
Tap your profile picture in the bottom right to go to your profile.
Tap at the top.
Tap Your activity, then tap Interactions.
Tap Likes, then tap Select at the top.
Tap on the posts you want to unlike. To filter your likes before making your choices, tap Sort & Filter in the top right and select your filter preferences, then tap Apply.