This wikiHow teaches you how to delete a Snap from your Snapchat Story or Memories. Since February 2017 you can't delete Snaps that have already been sent, even if you delete your account.
Steps
Method 1 of 2: Remove a Snap from your story

Step #1. Open Snapchat
This is a yellow app with a ghost icon.

Step #2. Swipe left on the camera screen
The page with Stories will now open.

Step #3. Tap on ⋮
This button is located in the top right corner next to My story.

Step #4. Tap on a Snap
Choose which Snap to remove from your story.

Step 5. Tap the trash can icon
You can find this in the bottom right corner of the screen.
- Tap the button Save (v) in the lower right corner of the screen if you want to save the Snap to your phone before deleting it.

Step 6. Tap on Delete
Your Snap has now been removed from your story.
Someone could take a screenshot or a photo of your Snap before you delete it. The sooner you remove embarrassing photos from your story, the better
Method 2 of 2: Delete a Snap from your Memories

Step #1. Open Snapchat
This is a yellow app with a ghost icon.

Step #2. Swipe up on the camera screen
The page with Memories will now open.

Step #3. Tap on a Snap or a Story
Choose which saved Snap or Story you want to delete.

Step #4. Tap Edit & Send
This option is found at the bottom of the screen under a sign that looks like a caret (^).

Step 5. Tap the trash can icon
You'll find this in the bottom left corner.

Step 6. Tap on Delete
The chosen Snap or story has now been removed from your Memories.