Removing an app from sale means it will not be available to anyone new, and would not be searchable in the App Store. However, your current subscribers would still have access to anything they've downloaded. As long as they've downloaded the app, and each issue - they will have it forever on their device, unless they delete it.
To remove an iOS app from sale:
- Log in to iTunes Connect
- Click on My Apps
- Click onto your app
- Click onto Pricing and Availability
- Under Availability, select Remove from sale
- Click Save
The status changes to Developer Removed From Sale. Within 24 hours, your app won’t be seen on the store.