Can I stop a software update

There are three steps that the process goes through after to agree to the update:

1. Downloading
2. Preparing the update
3. Updating

You only have the opportunity to stop it in the first two phases. Go to Settings > iPhone Settings > Airplane Mode > Turn on

Do you mean:

1. Stop it before it starts, or
2. After it is in progress?

Yess

you can delete too