After clearing Stage 1-12 you will be able to dismiss heroes at the Harbor.
Only Common heroes can be dismissed. Dismissing heroes removes those heroes from your team and compensates you with Dismiss Coins and, if applicable, all the resources used in leveling up any dismissed hero. Dismiss Coins can be used at the Dismiss Caravan.
You can individually select which Common hero you would like to Dismiss, or you can press Auto-Select, which will automatically pull your Common heroes into the dismiss slots. You may need to dismiss your auto-selected heroes multiple times if you have more Common heroes than dismiss slots.
Once all the heroes you would like to dismiss are selected, press Dismiss.
You can choose to automatically dismiss Common heroes as soon as they are recruited. Rather than joining your team, Common heroes will automatically be dismissed and you will immediately receive compensation rewards after recruiting them.