It is proper Netiquette to fix mistakes. Do edit and delete posts with errors.
A mistake is an action that is wrong. Mistakes in Social Media are posting information that is wrong. Wrong information can be a misspelling or misinformation entirely.
Fixing a misspelled word may be done by editing the post on some networks. Other networks require that the post be deleted entirely, then re-posted with the correct spelling and grammar.
Correcting posts with incorrect grammar or punctuation prevents them from being seen by more people. Posts appear in Social Media search results from a given network.
Wrong information that is entirely misinformation should be deleted. News agency’s post corrections. Some people post correction updates.
Correct small mistakes and delete misinformation because it adds value to the network.