Alternatively, if you're on 8.2.6 or newer, then you can perform the option from the AMPCLI as well:
AirWave Management Platform 8.2.7 on airwave.test.com
1 Upload File
2 Download File
3 Delete File
4 Backup
5 Restore
6 Support
7 Upgrade
8 Advanced
9 Security
10 Custom Commands
11 Enter Commands
q >> Quit
Your choice: 8
Advanced
1 Restart Application
2 Reboot System
3 Configure Network Settings
4 Set Hostname
5 Set Timezone
6 Shutdown System (halt)
7 Add File Transfer User
b >> Back
Your choice:
Option 1: restarts the AMP processes
Option 2: reboots the server
Option 6: shuts down the server gracefully