Application management is configuration-based, not device-based, so you cannot directly delete an application on one device. Here's what you need to do:
1. Open the configuration list and make a copy of the configuration managing your 5 devices ("Copy" icon)
2. Open the new configuration details and mark the application to "Delete" in the "Applications" tab.
3. Return to the device list, edit the device, and change the configuration to the new one.
Once you save changes in the device, it should get a Push notification about the configuration change and remove the application.