1. On the computer that is running MDM Gateway Server, run the Stop-MDMVPNServicecmdlet.

2. Open Control Panel.

3. Open Add or Remove Programs, select Microsoft System Center Mobile Device Manager-Gateway Server, and then choose Change.

4. On the Welcomepage, choose Next.

5. On the Repair or remove installationpage, choose Remove.

6. On the Remove Gateway Server Databasespage, choose Next.

7. On the Ready to Removepage, choose Remove.

8. On the Completed the Gateway Server Setup Wizardpage, choose Finish.

9. Restart MDM Gateway Server.

Reference