How to delete selected messages on instagram iphone?

Yeah, you can definitely do that. It's pretty straightforward on the iPhone.

Just open the conversation and find the specific message you want to zap. Press down and hold on that message bubble. A little menu will pop up from the bottom. You'll see an option that says 'Unsend'. Just tap that, and it's gone.

The main thing to remember is that this removes the message for everyone in the chat. It'll disappear from their view too, not just yours. It’s different to deleting the whole chat, which only ever removes it from your own inbox.

Easy as that, mate. You'll be sorted in no time.